With browser standards mostly converged, you don't need things that normalize and shim the DOM for you anymore. Firefox on desktop, Safari on iOS, doesn't really matter. It will mostly just work these days. You still need to be aware of device-specific capabilities, quirks with cookies & local storage, et. al., but this stuff is worth handling directly. Waiting on a 3rd party to get an iOS update bug resolved each year is not always great for business. Calling getUserMedia() is genuinely not a big deal if you can be bothered to read documentation for 10 minutes.
The other argument I see for using web frameworks is that it helps to organize the nature of work into some kind of popular pattern which then creates a common target for talent management. If you handed me a stack of resumes this morning and made me hire a developer, I would strongly prefer ones that imply vanilla/legacy web competency over those that enumerate 10+ popular JS frameworks. I am not looking for a modularized cog in a machine that I can arbitrarily replace. I want someone who can own the entire vertical and who understands why I would want that.
The interests of the front-end/back-end separation police are why server-side rendering seems to constantly get slandered. I've been excoriated by this new wave of developers on more than one occasion for suggesting that it is possible for one human to simultaneously understand HTML/CSS/JS, SQL and a single backend programming language. The most insane thing to me is that you could also just use javascript on the server to produce SSR content, but I've never once seen that not turn into a client-side rendering circus.
