How many times has it worked when you needed it to? If never, well, then you are certainly entitled to your opinions.
Inflatables have proven their worth over the years. No ... they aren't foolproof, as with most "unconventional" items. But if a person is uncomfortable or hesitant to wear a conventional vest because they are restrictive, then the inflatable is the way to go. And FWIW, there are far more positive outcomes with them than there are bad outcomes.
I fished without a vest on (except when underway) for many years and am glad that the inflatables are available. I wear one the entire time I am in the boat now.