My hot take: there's a general feeling of looking down on "web devs" or UI/front-end stuff. It's not really necessary to have React for a portfolio site, but it's not really an issue if they do.
There's a lot of strange smugfacing about using fit-for-purpose tools that translates into the shitting on people by the old-at-heart and the underinformed. Like, stepping away from JavaScript for a second, you still see people getting mad about C++ on HN and defending the use of C outside of a micro because "just be a good programmer" even though maybe a few dozen such good programmers have ever existed. It's very weird and it's one of the things about this profession that bothers me a lot.
I am fortunate that I have reached a place in my career where I can simply refuse to have that sort of person on my team.