I think it's because when you first use it, you're surprised to the upside about how capable it is and you don't care about small faults because you expected to correct for those anyway.

Then you get used to this new level of capability and subconsciously weight the errors more.

For all the talk, I see very few people sharing direct chat links that are the same query at different points in time with different quality of answer.

In fact, when I do similar things, I don't notice a change in quality.