>Whatever constitutes "bloat" depends on the context and preferences of a decision maker.

Same goes for whatever constitutes a necessity. I seriously challenge the idea that "websockets" are a must have.

Case in point, their lack haven't prevented tons of PHP, Ruby, Python, etc frameworks (all the tons of them that are not async/event based and can't handle websockets well if at all), from succeeding.

Heck, 1/4 of the web is based on Wordpress (including players like CNN, Forbes, Sony, and NYT blogs) and that doesn't even touch websockets, not to mention not being a proper CMS/framework in lots of other ways.