MSD does not require any training with instructors nor any extra knowledge
I'm with you. While some PADI specialty trainings seem to be worthwhile such as Rescue and Peak Performance Buoyancy. Other specialty trainings are total BS. Boat Diving specialty? You have got to be kidding me!!! Equipment specialty? Altitude Diving Specialty?
I, a non-instructor, can show a newbie all about "Boat Diving Specialty" in ten minutes. No charge.
I, a non-specialty trained diver, can execute altitude diving without having an instructor showing me how to read the altitude adjustment depth table. Or better yet, use a dive computer that automatically compensates for altitude.
I, a non-specialty trained diver, can learn how to maintain equipment just by hanging out at the shop and talk with qualified technicians and perhaps have them let me go at it a few times under their supervision.
Underwater photography? My photographer diver buddies can give me free lectures until I die of information overload. Heck, they'd even let me use their cameras underwater.
I wouldn't have a PADI Master Scuba Diver cert to impress chicks at the bar, but I would still be trained.
I am not against training. I am against giving PADI unnecessary money for BS training and go about wave a card that has zero meaning.
I'd rather spend that money on a cool dive watch that would surely pick up chicks and impress dudes.
Or learning how to safely do deco/multigas dives. Maybe a real wreck penetration dive class instead of what passes for PADI wreck diving training.