I'm somehow reminded of the Grim Reaper here. He tries to force his death ideal on everyone, while Yuri tries to force his muscles on everyone.
But the true Muscle Land were the muscles you built on the way. Which are also your friends. And were inside you all along. Muscles.
Now realistically speaking, I feel like the comment about speed should be true. Yuri breaks common sense with his Muscle Magic, but when your body is all bulky like that, you should have more trouble moving around, right? Not because it's heavy, but because the bulk gets in your way.
Even Muscle god's flexing is pushing in on his face and it looks like he can barely see.