When it comes to front end frameworks I've found most claims about them to be bald faced lies.
2) Things that would be less code without the framework, NOT counting the size of the framework against it.
Admittedly 1 and 3 have a lot of overlap.
There's no such thing as "complex UI rendering". UI is flipping simple since content dictates markup, and content + markup + device/user limitations dictates style... PEOPLE make it hard.
But because people ridicule HTML as "unimportant" or "not real programming", refuse to embrace separation of concerns, and in general just shove their head up 1997's backside there's this false perception that it's "complex". Utter and total BULLSHIT!
As evidenced by most UI "frameworks" clearly having been CREATED and maintained by people unqualified to write a single damned line of HTML or CSS. Just look at the source of any bootstrap, tailwind, w3.css, etc, etc, examples.
That said, I have ZERO clue what you mean by "domain code"... or what business to business has to do with anything.
JS for nothing and your scripts for free... that ain't workin', that's not how you do it. Lemme tell ya, these guys ARE dumb.