1. Many of Pride's champs are or have trained BJJ
2. All of Pride's champs have trained SOME SORT OF GRAPPLING (Judo, Sambo, BJJ, etc. which have many things in common)
3. Noones telling you that you have to do BJJ, rather they're suggesting it. BJJ has been proven to almost never be bs.
4. Its the Practictioner, but the art has lots to do with it also, if you don't train against resistance, then you're not gonna be good at fighting.
Bringing up your other threads,
1. Looking cool doesn't equal effectiveness (see- almost all of Pride's Fighters)
2. Some martial arts just have more frequent and lower quality standards/don't spar or train against resistance (see- Noone in Pride does _ing _hun)
3. Die Now