The Rolling Stones have been singing live for over 50 years now. The fact that some singers do it all just shows how lazy people can be.
Then again, I heard that bands like The Monkees used to do it back in the 60's.
I feel like real rock bands are going to be the most likely to actually sing live during their concerts. I didn't know that about The Monkees, but I also don't know if that surprises me or not.
I would guess that the people who have had to quit and/or postpone tours due to vocal chord injuries are probably the real deal.