Interesting, I think for the older generation me included at the age of 45, it can be jarring to miss the visual marker of the capital letter in the beginning of a sentence. I have been online for 30 years and have certainly written my fair share of poor grammar, missing punctuation and probably missing capitalisation as well. I think the surprise comes from this being an article on the internet and seems like a design choice.
To me, writing in full, formally correct sentences, being careful to always use correct punctuation, starts to feel a little pretentious or tryhard in some contexts.
It doesn't feel too much like that here on HN. But on reddit, I use less formal structure most of the time, and that feels natural to me.
15 years ago, it was incredibly common to see folks texting things like "c u ltr". It made its way into instant messaging (where folks had a keyboard), but slowly disappeared once everyone had smartphones that autocorrected everything. I don't think it's strange to see that people prefer it stylistically. Text has very little in the way of showing emotions or intentions, so everything you can do to alter that is something to be used. People want to be less formal sometimes.
