Rubbish. Most of the stuff you’re listing is handled by OS and frameworks themselves, you don’t need hundreds of SE to handle RTL or a11y. I work in one of those companies, most people just regurgitate existing shit into another form of shit and collect salary (not complaining, as I’m one of them, but let’s be honest).
We live in a time now where libraries are free and plentiful and pretty good. It is easy to forget that this was not the case for the vast majority of time that computers have existed.
Chrome’s original design definitely predates our current rich ecosystem. Plus, V8 and Chrome’s performance profile are demanding enough that there would be a pretty high bar for those dependencies anyway.
This is plain wrong. For a browser, a11y doesn't just get handled by the OS automatically. In general, claiming a11y is easy or will be done by someone else is bordering on evil.
The original Edge had to switch over to Chromium because it was hard to build a compliant accessible browser from scratch and this is Microsoft we are talking about.