Because here's the thing; LLMs tend to do best with languages and frameworks they have training material from. At the moment, that means they're amazing at coding in JavaScript, PHP or Python, and with frameworks like React and Vue.
But if you move away from that, you'll likely need to do a lot of your own AI training, or wait for the public ones to get enough material to be usable with your new framework or language. You can see it for yourself with any niche language or setup; generative AI simply won't understand the material well enough to be any use whatsoever.
So does this mean we'll see companies stick with existing frameworks simply so they can use AI to vibe code stuff? Or even that new frameworks and languages may not catch on at all, since there's not enough training material to make them usable with AI tools?