Where are all the supposed productivity gains going on HN?

At best, average credibility across HN from what I can see has remained roughly the same, though it realistically went down a bit compared to 3 years ago. (When GPT-4 became widely used with decently useful outputs)

Same for the average credibility of submissions, YC startup batches, and so on.

The average level of detail of HN comments is not any higher either.

There are more comments and more submissions per day, but that seems due to more accounts?

So observably, overall productivity gains seem to be nil, or even slightly negative.

It may be that HN and YC is perfectly insulated from broader societal productivity, but I doubt that.

What could explain it?