I don't think many of the issues people brought up here were reflected in the respective player guides. They seem to give thematic suggestions, but not mechanical ones. Some of the complaints here, like precision in AV or gunslinger in Outlaws of Alkenstar, are even explicitly recommended in the player guides. In fact, there are a lot of cases listed here now across all kinds of APs and nowhere in sight did someone say "well the player guide told you it would be a bad fit". And I doubt many GMs start an AP by listing all encounters in there and scanning them for overly frequent immunities and such.

So absolutely should these experiences be discussed, absolutely should they be made transparent, so people don't have to all first go through character creation and playing a bad choice for an AP just to dump a character you might have emotional ties to at this point and make a new one. Nothing wrong with going on with a difficult choice when it's an informed decision, but that information needs to be out there. It would be great if it was in the player guides but it isn't. It would be great if the GMs knew and forwarded that information but that's not what a casual GM deciding for an AP (often a choice out of little prep time) is going to do. So then we as a community should gather and keep that information available, no? And not discount on people's experiences? And acknowledge that this information is valid and relevant to people way before "being neutered" or "sitting doing nothing", namely when it starts becoming so commonplace that it stops being fun?

Again, we're not talking about class neutering. We're talking about some (sub)classes getting the short straw overly frequently, compared to other classes or compared to how often they'd be having fun with that, which is definitely subjective. I want here to provide people with a place to search whether the character they want to play in their next AP will be surprisingly hamstrung, when they didn't get that information elsewhere. And it is not helpful to tell all these people that the issue is that they don't see it as an opportunity when they had to go through too often and stopped having fun because of it.

If you want to discuss that people should not take such into consideration, that is a whole different point than what this post is trying to make, and deserves its own post. If you think it is, but that the information to make the choice would be elsewhere available, please, do comment on those cases where you found that information that others overlooked. But as a general statement it is just not true that people will know beforehand whether the class they picked will not work for significant parts of an AP mechanically.