I think the people saying this are not wrong, but they are also completely missing the point. Apple is not expecting its users to run out and upgrade their watch every year, which is why this year’s Apple Watch 7 wasn’t never going to be so significant an improvement over the previous iteration. It’s likely going to be the case for next year’s series 8, or the one after next.
You have to consider the target audience for the series 7, which are like those still on the series 4 or earlier, as well as people who are still not wearing one. The upgrade cycle for the Apple Watch is likely every 3-4 years, and so it makes sense for Apple to pace itself accordingly.
It’s simply not sustainable to expect Apple (or any other company) to cram so many improvements into each generation of Apple Watch. It’s wasteful, and not everyone is going to upgrade anyways.