Most of us devs had "separation of concerns is critical" drilled into us for many, many years. For that reason alone, JSX just gives me the baddest of smells when I look at it.
The fact that Wordpress runs so much of the web sometimes wakes me in a cold sweat. If you're a dev worth their salt and knows proven engineering and design patterns, then Wordpress code is absolutely terrifying to look through.
Yup, hard truths: vanilla JS is far less readable and clunkier than just using jQuery to do the same thing. Also, not everyone needs or wants to move to a shadow DOM framework with a zillion components and high complexity. If you're building a SPA or PWA, yes, absolutely, but for the vast majority of us who use a traditional backend/CMS-driven site with server-side rendering where client-side interactivity is needed, jQuery still does the job really nicely.
I just can't bring myself to like or be encouraged to use any form of approach that binds together logic and presentation. It looks and smells like terrible programming. Separation of concerns matters and, as you mentioned, more seasoned devs had decades of this being drilled into us.
This was the end result I came to as well after the bigger frameworks started gaining popularity. I work primarily solo in a single organisation with server-generated (CMS driven) websites.
Yes, I could have replaced jQuery with Vanilla, but the syntax for jQuery is still so much simpler, and I care about my limited time and productivity. For me to switch over to something like React would be complete overkill.
Again, as part of a bigger team, like you, I'd most likely consider a different approach.