Beyond Selidor

I agree with you, although I'm not sure I'd call every 'classic' novel with a child or teenage protagonist YA, since 19th-century reading habits and understanding of genre was a bit different to our own. I'd probably say that Harry Potter really kicked things off, and I can remember a huge number of thinkpieces about 'adults reading children's literature, isn't that weird?' in newspapers in the early 2000s. (And there were issues of the HP books published with 'adult' covers so that people wouldn't feel embarrassed reading them on public transport.)

I think the YA Twitter essay suffers in that its two central theses are flawed. She places the blame for the toxicity of the YA community at the feet of a) Twitter and b) the fact that its readership is mainly adults and the marketing expectations reflect that. Whereas I think the toxicity flows from the paranoid attitudes of scarcity which encourage authors to view other authors not as their colleagues but as their competition (and so accusing another author of writing a book full of problematic content becomes a prudent marketing strategy), and the fact that professional marketing teams have been replaced by a requirement for authors to market their own work on social media, especially on Twitter (which rewards loud pile ons).