@donkeypong - that was an 'illuminating post'..:)
I think you got it spot on when you said work of this magnitude and quality over a long period of time simply is not possible with the distractions of a typical life - and given that modern life is filled with a multitude of distractions, it's not surprising that this kind of art is so rare today..
I totally agree with this also, it really puts it into perspective. These works would be your sole purpose in life, you would do nothing other than work on perfecting them. No wonder there were so many amazing masterpieces from the past!