It's not just pushing web-based readers: I think the largest thing behind Google Reader nostalgia was social. It was Google's biggest social network to date in terms of daily active usage. (They'll throw stats that Google Plus did "better", but who is nostalgic for Google Plus, exactly?) That's why it got the closest to breaking mainstream: it wasn't just "go out in the wilds and hunt for RSS feeds on blogs" like most web-based readers appear to be to a new user, but "hey, follow my Gmail email in Google Reader and I'll share some cool things I read and then you can also yourself subscribe to where I got that". It was the conversation around stories. It was the network effect of all the Gmail users at the time.
Web-based readers today are better than Google Reader was in terms of features and data sources supported, etc. (I'm partial to and pay for Newsblur myself.) But none of them have the network effects or "social scene" of Google Reader at its peak. Likely none of them ever will. They are competing today with Twitter and Facebook. Those are the spots where people share and comment on the articles they read today.
Considering that the social angle was not what people bemoaning the lack of updates for Reader, then its shutdown, complained about? I don't think that was the majority usage by far. You (and the two people responding to that effect) may be literally the first people I've seen bring up the social functions of Google Reader in conversations and articles as something they missed since it shut down.
That said, if you want a social network, they exist. If you want an RSS reader, they exist. If you think reading web pages and adding feeds to an RSS reader is going into "the wilds", you may not want the latter.
I think you missed some things in my comment. I have an RSS reader and it has social features. I'm happy with it and have used RSS pretty much continuously from its early days. I agree with you, on paper feature-for-feature, my RSS Reader of choice today is better than what Google Reader was in many ways. What it doesn't have versus Google Reader, where I still draw some small nostalgia for Google Reader is Google's network effect (nor does it have Facebook's or Twitter's).
You found it weird that people are so nostalgic about Google Reader and said you didn't see why people are so nostalgic about it: my point was that a big thing that people who are nostalgic for Google Reader miss both directly and indirectly was its social features and their network effect. At Google Reader's peak I did have non-technical friends that had no idea what RSS was or how it worked, but they followed a bunch of their friends socially in "that reading thing connected to Gmail" and sometimes picked up that they could subscribe to other feeds just by subscribing to feeds they saw in friends' feeds. That was a big deal for almost-mainstream adoption. Most of that has moved to other social media today (Facebook and Twitter) and that's why "RSS is dead" according to all the headlines, but for a brief period Google Reader was people's "Twitter" and rather than top-posting short quips and a link to an article some of the time every "tweet" was bottom-posted in reply to articles. ("It was a more cultured social media for a more civilized age," in old man words.)
It's not unlikely that you don't have nostalgia for Google Reader simply because you weren't even indirectly aware of its social features. I'd wager a lot of the people that truly have nostalgia for did take some advantages of its social features. I know some friends anecdotally who still don't know what RSS is today but are still nostalgic for Google Reader. I've tried to convince a few of them to join me on my RSS Reader of choice and I can use its social features to teach some it in a similar way to how we all used to use Google Reader, but "no one" but me is still left in my RSS Reader of choice among that original group and most "everyone" is on Twitter or Facebook. It was the network effect that made Google Reader nearly mainstream, that put RSS to the closest to the mainstream it may ever get.
Web-based readers today are better than Google Reader was in terms of features and data sources supported, etc. (I'm partial to and pay for Newsblur myself.) But none of them have the network effects or "social scene" of Google Reader at its peak. Likely none of them ever will. They are competing today with Twitter and Facebook. Those are the spots where people share and comment on the articles they read today.