I'm sure most people especially anyone reading this is familiar with MMA. I trained MMA at a gym for a couple years and there's a lot to love about it. I one of the more unique skills in MMA that I wanted to develop was wall wrestling. It's not a skill you'd find in any form of olympic or folkstyle wrestling, nor any jacket style of grappling as far as I know. Every other grappling sport is done on a mat without walls. This aspect in my opinion gives MMA something unique about it and it's a difficult skill to develop. The wall really does change a lot in terms of what techniques you can pull off. For example, even if you had double underhooks on someone against the wall, you wouldn't be able to hit a duck under without pulling them first away from the wall. Additionally a blast double requires you to alter your technique to work against someone leaning on the wall. The wall also makes a great anchor point to pin someone's wrist when in the clinch or fighting for grips.
Now and then I hear some traditional martial artist claim that MMA isn't as effective for fighting as their style because MMA has rules and street fighting/self defense has no rules. I find this argumnet pretty silly. MMA is a sport, but I think the fact that it's a sport has actually aided its value in some way. In the early days of MMA, people were mainly coming from one style or another, with very few having multiple disciplines under their belt. It was through the process of testing themselves against each other, that people determined what worked and what didn't work. To claim that an MMA fighter would be at a disadvantage in a self defense situation because you're ready to strike the groin, poke them in the eyes, fish hook them, etc is farcical. MMA fighters aren't incapable of doing these techniques, they simply don't for the sake of safety. Someone who has a perfect jab would be able to eyepoke or papercut someone much better than someone who didn't have that crispy jab technique. So let's put that argument away, MMA fighters are in fact some of the most if not the most equippped people for street fighting situations.