Who's blaming anything? The
average carnivore diet in the Western world, is a million times unhealthier than the average vegan diet, and chances are, your average meat eater will suffer from oncoming heart problems and a slow clogging of the veins, etc. Going to a gym is not relevant, that's something that's good for you regardless of diet.
Also, meat is not required in that equation, and I could point you towards more than a few vegan bodybuilders, mixed martial arts fighters etc who would be happy to tell you that also