It’s generally true that the people who come up with the first interesting idioms in a new space get an outsized influence on the community. It takes a while for people to borrow or steal their ideas and run with them.
On the plus side while the AI can’t write in that language there’s money to be made doing the work organically.
Yes, but I think it's also true that LLMs are acting as a force multiplier to the underlying effect you describe.
Something like (my apologies to maths for the abuse) LLMs are adding one to the exponent of the adoption feedback cycle.
The knowledge bottleneck is in the human population, which is then reflected in Stack Overflow and blogs, which is then reflected in LLM's.
LLM's aren't doing anything special to stifle new tech adoption. New tech is harder to adopt because it's new tech, because people in general are less familiar with it.
(And there's a little bit of a training delay in LLM's updating, but that's a minor aspect here compared to the years it takes for a new Python package to become popular, for example.)