Ignorance, apathy, and wishful thinking -- the majority of people using these garbage off the shelf "frameworks' are generally unqualified to be writing a single line of HTML or CSS, much less JavaScript. They don't understand HTML's purpose, they don't understand accessibility or user experience, and they don't know enough about general programming to even have a valid opinion if any of that crap is worth a flying purple fish!
When people talk about any of this junk as being "easier" or "makes you more productive" I genuinely have ZERO huffing clue what the f* they're talking about!
Though I suspect a lot of that is, well... take what I'm always saying about the mentally enfeebled half-witted trash that is jQuery. EVERYTHING I've ever seen done in jQuery clearly and cleanly falls into one of three categories.
Stuff that would be simpler, clearer, and faster loading without the dumbass framwork.
Stuff that's HTML or CSS' job and has little to no business even having JavaScript involved.
Stuff that has zero blasted business on a website in the first place!
... and that's just talking front end frameworks.
There's a reason I refuse to call my own little JavaScript helper library a "framework". I don't want to change how JavaScript works -- I sure as hell don't want to promote bad practices like jQuery and its ilk do... I just want to plug a few smaller gaps. probably why half my codebase is polyfilling some ECMAScript 5 and 6 stuff for legacy IE
But I'm one of those developers who when I see markup being slopped into a page innerHTML style, or even just building markup with strings instead of leveraging the DOM, I automatically assume I'm dealing with someone who still has their cranium wedged up 1997's rectum.