If you think about economic value, you’re comparing a few large-impact projects (and the impact of plan9 is debatable) versus a multitude of useful but low impact projects (edit: low impact because their scope is often local to some company).

I did code a few internal tools with aid by llms and they are delivering business value. If you account for all the instances of these kind of applications of llms, the value create by AI is at least comparable (if not greater) by the value created by Rob Pike.

One difference is that Rob Pike did it without all the negative externalities of gen ai.

But more broadly this is like a version of the negligibility problem. If you provide every company 1 second of additional productivity, while summation of that would appear to be significant, it would actually make no economic difference. I'm not entirely convinced that many low impact (and often flawed) projects realistically provide business value at scale an can even be compared to a single high impact project.