I'm currently holding a 1100 days of streak of Italian in Duolingo, so I think I am entitled to drop in my 2 cents ;)
To some extent I agree with the critique. Would I be able to write an assay like the op in Italian? surely not. Is their marketing annoying? yes, very much. Is the platform perfect? far from this. However - after 3 years with Duo I am capable of having causal, simple conversations, I can navigate most of the websites in Italian, I understand most of the marketing emails, I can write simple emails myself. I trust this is mostly due to DuoLingo - building the vocabulary and quickly recognizing the patterns (and It was not super simple, my native language is Polish, and I was learning Italian via English interface - there was no Polish-Italian course back then, now there is one but it's just very low quality).
Duolingo helped me build a habit, knowledge of words and patterns. During the 3 years I've spent with the platform I made trips to Italy, I tried talking to people, tried to read texts and and explored some grammar myself. About a month I go feeling I've outgrown the platform I started doing 50min conversations on Preply platform and I am now confidently moving into stage where I can build longer sentences, use past and future tenses and irregular verbs.
In my discussions with friends I emphasize that IMHO Duolingo alone is not going to teach you (complete) language. If you have a goal to learn a language (in general, not on Duolingo) and you use it as one of the tools - it could be really helpful.
I agree with your last point. I get the criticism of Duolingo and it is fair, but I can't agree that it is completely useless. I learned/am learning French. I can get by with non-English speakers and people won't immediately switch to English when they hear me.
It took about 5 years of on and off practice. Not sure how much actual time I put in. Duolingo was one aspect, where honestly I probably learned like 75% of my vocabulary. I also have a French wife and friends, took classes, hired teachers, watched movies, read news, etc, etc, etc. I probably could have got to where I am without Duolingo but I'll never know. Learning a language is a pain in the ass and I don't think any one thing is really going to do it. Duolingo is free and can be one aspect out of many that will help get you there.
I do feel like many of the Duo critiques are strawmen. Of course no single method will lead to new language fluency. Even full immersion requires practice and often classes.
I use Duo, Pimsluer, live in Italy, and will start classes in a month or so. Duo is a fun game that also helps with my language journey.
Duolingo was helpful for me to expand my Spanish vocabulary, but it definitely did not teach me the language itself. Some of the most critical linguistic concepts are buried at the top of stages and not brought up in the gamified lessons themselves. I'm in a privileged position since my wife is a native Spanish speaker, so I quickly began to grasp how much Duolingo wasn't teaching me and how much speaking Spanish with my wife (and watching Spanish-language shows without subtitles) _was_ teaching me.
I think what you say about having 'outgrown' the platform is basically hitting the nail on the head here. Duolingo knows their audience is people just looking to start learning a language. That's the top of the funnel and therefore the place where they can capture the most users, which for them makes sense because the majority of users are monetized through ads.
There are so many other platforms around Duo though, Preply being one of them, that go a lot deeper with techniques that are great once you have that baseline understanding but maybe wouldn't work so well on people who are maybe just starting to try to commit to a habit. If from day one you make someone sit down and have a 50min conversation they are much more unlikely to be doing it 7 days later (and therefore watching ads) than if you just introduced them to a few basic words and concepts.
So i don't know if this is necessarily a bad thing that duo is built this way, it's just serving one audience. And that audience are the ones that need the most help in habit forming and motivation - hence the gamification is strongest.
Sure maybe they've gone too far, and maybe the way they've done some features like the leaderboards and leagues kinda sucks but even if these things are always a bit marmite, they do work for a lot of people. We've built a very similar system in trophy and we see the data - streaks, achievements etc really do work.
I do think if duo made the leagues, points, challenges etc more friend-focused rather than being put into cohorts of people who you have no idea who they are then that would be better. I think at one point I was asked to 'import my contacts' but tbh phone contacts are such a dead feature in 2025 that I don't want some rando that I spoke to 10 years ago being my friend on Duo lol. If I had a way to discover my friends maybe by username or whatnot then that could be better. Not sure if they already have this...
IIRC the CEO(?) of Duolingo was asked what he would choose if he had to choose between a more effective language course and more gamification. His answer was gamification, because the best course doesn't help anyone if noone shows up.
So at least they know that it's not the best way of learning a language.
To some extent I agree with the critique. Would I be able to write an assay like the op in Italian? surely not. Is their marketing annoying? yes, very much. Is the platform perfect? far from this. However - after 3 years with Duo I am capable of having causal, simple conversations, I can navigate most of the websites in Italian, I understand most of the marketing emails, I can write simple emails myself. I trust this is mostly due to DuoLingo - building the vocabulary and quickly recognizing the patterns (and It was not super simple, my native language is Polish, and I was learning Italian via English interface - there was no Polish-Italian course back then, now there is one but it's just very low quality).
Duolingo helped me build a habit, knowledge of words and patterns. During the 3 years I've spent with the platform I made trips to Italy, I tried talking to people, tried to read texts and and explored some grammar myself. About a month I go feeling I've outgrown the platform I started doing 50min conversations on Preply platform and I am now confidently moving into stage where I can build longer sentences, use past and future tenses and irregular verbs.
In my discussions with friends I emphasize that IMHO Duolingo alone is not going to teach you (complete) language. If you have a goal to learn a language (in general, not on Duolingo) and you use it as one of the tools - it could be really helpful.