Yes,even in traditional martial arts an emphasis is given to physical conditioning the idea is given that if two people are well matched technically strength will be a deciding factor.In any case it helps a lot with more than just fighting, it can help some guys who have a hard time with weight cutting, it can help to give someone a mental edge as much as a physical edge because fighters know apart from their nutrition before they get in there to fight this is one of the big things they can have a lot of control over if they do it correctly.At the higher levels everyone has top quality technique so the deciding factor will come down to strength,not so much endurance training though that helps, the point is the stronger fighter will have to exert less effort than compared to his opponent. an example let's say an opponent has to use 80% capacity of his strength at all times during the fight but the stronger fighter is using 40-50% by comparison in that regard it's easy to see who will tire and break mentally first thus giving the stronger fighter tactical and physical advantage.In the grand scheme of things with S& C it's not in an attempt to build overwhelming power against technique but making the body stronger so that the technique will work better, true skill is a marriage of technique and strength or if you prefer technique is applying your strength correctly

It's necessary if you want to be the best fighter you can be. Your techniques are your bullets; physical conditioning is the gun. If you're out of shape, you won't be able to fight as well, or as long. Certainly, there's no DISadvantage to being stronger, faster, more flexible, and more fit.

I do mma but I mostly just stick to the martial arts stuff like rolling, wrestling and sparring. I'll do a little weight training and runnning, but I see a lot of fighters doing the cross fit type stuff. pulling sledes, battle ropes, feet drills and jumps, all that sport conditioning stuff. But is that stuff really necessary?