We occasionally practice 15m 'out of air' swims along a 15m line in our local quarry during practice dives.
This is with full mental preparation, knowing exactly what will happen and what you need to do, and an instructor's octopus about 2 inches from your face during the entire swim. Yes, it's bad vis, cold water and more gear than in Mexico, but still an applicable comparison.
Most of our club's divers find this exercise stressful, and many don't always make the full 15m.
I can tell you, 10m is WAY too far for safely tackling out of air situations, especially if your buddy is minding his own business, probably looking away from you and swimming in another direction.
All I hear you saying is:
"I don't feel like wearing a seatbelt in the car is necessary. I never wear it and never had a problem with it."
Safety is not the absence of accidents. Safety is being equipped and prepared to deal with incidents so that they don't become accidents. Just because you haven't had an accident doesn't mean you're diving safely. It's just that you haven't been in a situation where proper training and mindset was needed to keep you or your buddy alive.