It's that, but it's also that the incentives are misaligned.
How many supposed "10x" coders actually produced unreadable code that no one else could maintain? But then the effort to produce that code is lauded while the nightmare maintenance of said code is somehow regarded as unimpressive, despite being massively more difficult?
I worry that we're creating a world where it is becoming easy, even trivial, to be that dysfunctional "10x" coder, and dramatically harder to be the competent maintainer. And the existence of AI tools will reinforce the culture gap rather than reducing it.