Yeah, the fact that people are comparing Ohtanhi to Ruth is a joke. Ruth lost 30 years Home Runs to long fences.
The only thing you can do is compare a player to his contemporaries. And clearly Ruth was the most dominant player of an era. Of course advances in technology, nutrition, training, etc. make today’s ballplayers much better than the players of a hundred years ago, in absolute terms, but greatness is something that is measured relatively.