Yes - for people who do not have scuba attached to them. As i said, snorkels are very useful tools if you decide to go snorkelling. This thread is about SCUBA though which is completely different.
This tread was about have low air and having to do a long surface swim, and how a snorkel would have help allot in this saturation.
You are the one pushing about not bring equipment because you think it is not necessary, as you stated earlier.
You then try to tell me that I should uses my emergency reserve for a long wait or surface swim and that having a snorkel is useless in rough seas. It is my emergency reserve, I should do with it as I see fit. And a long swim 500psi will not last too long at all.
To me it seems alike allot of babel from you whenever someone tries to point out that there is nothing wrong with having a snorkel with your scuba gear.
Like saying that a snorkel is useless in anything about 5ft waves. Then you try to defend your point with nonsense, the fact is a snorkel with proper training will be very useful in up to 20ft seas, as the coast guard and navy rescue swimmer proves every single time to go out in bad weather.
I did not say that you are wrong for not using a snorkel, I just agreed with the OP that a snorkel would have made his swim easier. I am not the one trying to push his personal preference onto everyone.
If you are a good instructor, I hope you show your students the right way to use their equipment. And let them choice what they feel the want and feel safe to have on their dive rigs. The key is that they need to feel safe and comfortable to truly be relax and enjoy scuba.