Just google something like "mma - boxers vs wrestlers" and you will find a pretty big argument and controversy for both sides on that topic. I personally fall on the side of the martial arts/wrestler people, but that's just my opinion.
Does anyone remember the beginning years of popular MMA? Back when UFC didn't have weight classes and matched different styles? You would have wrestlers fighting boxers fighting Karate experts.
In the end they found Brazilian Jiu-Jitsu and wrestling came out on top the most, with the random win to a good stand-up knockout. So now we get fighters with a mix of those three. Too much stand-up (boxing) and you get submitted, too much BJJ/wrestling and you may get knocked out before you take it to the ground.