You have to submerge a good portion of a filter before it can pull water instead of air through it. So you either have to be really unlucky or really dumb to put yourself in a situation where you could hydrolock your engine.
Bypass valves are pretty useless IMO. They do not completely protect your filter if it was sprayed with water directly. You'd have to be an idiot to drive it through a deep puddle and completely submerge the filter, thats when the bypass valve actually works.