I actually think that the pushback is to the position that you absolutely need it for every dive, which from what I can tell is the official position of at least one major training agency. Now you could say that this is just for training, but most infrequent divers (i.e. most certified scuba divers) just do what they learned in training when they go diving, so it tends to carries over.
I think that the "anti-snorkel" posts can be broken down into two categories:
- Objection to the idea of wearing it on the mask
- Objection to the idea that you need it for every dive, and if you don't have it you are putting yourself at risk
I can't think of anyone in this thread or elsewhere objecting to the idea of carrying a foldable snorkel in case you are in the situation where you want one unexpectedly. Saying that people object to that is kind of a straw man argument.
I guess I can see that it would be convenient or comfortable in some circumstances, but I don't see that not having a snorkel - even on an ocean dive - would be a major SAFETY issue. And that's an important distinction. Unless, I guess, you are diving in situations where helicopters and rocket propelled grenades are a consideration.