There are people who do care about that, but it’s astonishingly rare. Just consider it abandoned knowledge. Most of the people who continue to care about these things do so in open source contributions far away from their employment.

As a proof occasionally somebody will post something on HN about performance (asking for guidance, showing off a refactor, claiming performance is a critical must, whatever). I show them how to achieve load times of less than 100ms on a OS like GUI with full state restoration and the feedback is always the same. Either they can’t hire anybody who is capable of following that guidance or the juice isn’t worth the squeeze. Nothing in the guidance is challenging. It’s just not framework bullshit.