> Is it just that developers are now satisfied with the semantics being in their component names and props, and don't care if it actually gets rendered as undifferentiated divs?

Basically, yes. Also, components often require extra div-nesting for robustness, and then there's the obfuscated classnames (CSS-in-JS), and the way responsiveness tends to be done these days (crude media query helper components that show/hide duplicated subsections of DOM for different devices). This all means the rendered DOM in devtools is bloated and hard to read anyway, so there's less point in caring about keeping it nice and clean.

Also, if you're mostly focused on building individual components, you probably don't feel as much ownership over the page as a whole, so you don't think about how your rendered DOM affects the document outline. Without that bigger picture, semantics isn't as interesting.