Either way the OP has to both learn and deliver a product in a short time frame. It just makes more sense to cut out all the unnecessary bullshit developers use to compensate with.
I think it's way quicker to put out a MVP with a good UI framework (something like MUI or Chakra or Ant) than to spend a lot of time building up primitives from scratch.
It's like the difference between writing Visual Basic and C++ or whatever. Different use cases.
Without knowing what the OP is actually trying to build, it's hard to say what's more suitable.
I wouldn't necessarily default to vanilla OR React. It really just depends.
I was in that line of work long enough and have heard that false analogy enough to know that it’s people pretending to be arrogant to distract from their stupidity. Rephrased its really just: I shouldn’t have to form of whining because they never learned in the first place and are embarrassed by what super beginner things they absolutely cannot do.