It's stuck in time, has no support, only core devs can expose newer DOM apis (and when I say newer I mean released in the last 6/7 years). Very hard to hire for, not LLM friendly.
I guess if every piece of tech you learn is about finding a job or using LLMs that might matter.
But again, I don't think no support matters. How many DOM apis do you know of in the last 10 years that are essential? There are sites on JQuery 2 running fine.
