I think there is many layers of talent in all of this. On screen VS off screen.
At lot of success on Youtube is being in the right place at the right time. Pick a niche category of videos and it's easy to become #1. Look at channels like AvE or The Hydraulic Press channel; both put out some of the poorest edited sh*t out on the internet, but are both successful because it's a niche community and the content is somewhat "interesting". Contrast that to someone like Casey Neistat; there are more people vlogging on Youtube than you could watch in a lifetime, but he comes out with some amazing editing and he becomes massively successful, despite him not being all that "interesting". The guys who run AvE and the Hydraulic Press channel both are arguably talentless people, while Casey is.
Hell, even back in my day of Youtube, being able to play the algorithm to force videos onto the homepage of Youtube was a talent of its own.
As far as the Youtube star/celebrity, you've got to call them something. These are people with dedicated audiences of millions. I wouldn't call them celebrities but they aren't nobodies.