Try it in high choppy seas where even staying at the surface is difficult when hanging on a line out from the boat. You get exhausted pretty quickly. Then try swimming a distance, against current, in gear, under those conditions. After you do that then tell what every diver should be fine with.
The snorkel was a wide bore semi dry and did not fail. It just couldn't be used in the conditions without taking on water continuously.
For the record, it's the know-it-all posts like this that keep me from posting the full account. Most include the phrase "any diver should be able" - as above, go do it and then talk to me. They also say "I don't see how". Of course you don't. I didn't either - till it happened to me. Do you really think I would have done this on purpose? Since you weren't there, since it didn't happen to you, I wouldn't expect you to see how it could happen. But your post implies that it couldn't and that it was ... Well let's leave it there.
Maybe I should post the full account, along with all of my analysis of my bad decisions and what I would do differently. That would bring the "perfect divers" out in droves. It would make it easy to populate my Ignore list. It would also identify those who try to be honestly helpful as opposed to patronizing and condescending, those whose input and opinions I can trust and respect. Might just do it.
Also for the record, one of those people who honestly want to help reached out through PM. They were supportive and reviewed the full account and my thoughts and offered suggestions. More importantly, they identified some things I hadn't thought of and allowed me to identify some additional equipment, that will go on every dive from now on, that would have made this experience far less threatening and far more survivable. Sincere thanks to that person.
It sounds like you got some valuable information that may also help others, I hope that you do decide to share it.