I liked bootstrap, in my world (non front-end) it was a standardised way to decide on mobile screens etc. I am old so bear with me, but that was a whole thing. There was no \SPEC\ these are the things that need to be established and done, it was decided by browsers in the end.

Now, browsers are built mostly by those who ran(today it's a mess) the web. HTML schema and spec... I've never met anyone that's contributed to it in the last 10 years.

The best developers and engineers I do know, don't consider it anymore. It's been done in our eyes. The big companies took over.