No one is arguing the Michelangelo wasn't a fantastic and talented craftsman, far more so than our made up modern artist. Everybody agrees that to do what he did takes decades of practice and schooling.
But equally, that is not what made Michelangelo a great artist. There where dozens of extremely technically skilled painters that lived around the same time, none of whom most people have heard of. So if you want to argue for Michelangelo as a great artists, you cannot simply say "well he was very good at painting and made pretty pictures". Lots of people did that, so why is Michelangelo famous today and none of them.
But equally, that is not what made Michelangelo a great artist. There where dozens of extremely technically skilled painters that lived around the same time, none of whom most people have heard of. So if you want to argue for Michelangelo as a great artists, you cannot simply say "well he was very good at painting and made pretty pictures". Lots of people did that, so why is Michelangelo famous today and none of them.