Isn't a lot of this complexity going away for good reason? Browser compatibility was only an issue because browsers didn't stick to the standards closely enough. It's something that's not supposed to be noticeable at all.

And let's be honest, one of the best changes front-end development has seen is how previously complex problems now have built in, easy to use solutions. Yeah you could say it was harder to code layouts when flexbox and grid didn't exist and you had to deal with floated elements and absolute positioning, but the new setup is just better for everyone.

Customising select menus used to require lots of CSS and JavaScript to remake the element. Now browsers are implementing features to let you customise default select boxes the same way. Having an element expand to auto height use to involve JavaScript. Now it's something you can do in CSS alone. Creating modals used to involve writing CSS and JavaScript. Now an accessible and efficient version can be done with built in tech.

Meanwhile JavaScript frameworks are really just continuing the pattern started by previous tools, like WYSIWYG editors, Content Management Systems, jQuery, etc.

At the end of the day, any tech that gets more advanced will lower the skill floor and reduce the need to care about those minor intricacies. Most people don't need a particularly advanced solution to their problems, so whatever system can automate away most of the work will get used for that. It's not unique to web development or software engineering.