[apitman]

This is one of the biggest reasons I see people citing for Vue>React. I think it's a very easy argument to defend, but I'm sincerely curious how big of a role this plays. Is it really that common to change the HTML/CSS of an app without also requiring changes to the underlying JavaScript? I have no doubt it happens, but I'm wondering if it happens often enough to justify claiming superiority of one popular web framework over another.

Beyond that, out of HTML, CSS, and JavaScript, by far I find CSS the most difficult to work with and get to behave the way I want. Are there really a lot of designers who are experts at this language but don't know any JS?

I think you might be able to measure some of this. I wonder if you could look at some popular web apps that have separate HTML/CSS/JS files and look at the proportion of commits where only the UI changes, vs commits where you have to change the UI and the JS. The hypothesis being that in general you need to change your JS, and thus require a full developer anyway.