[stronglikedan]

IME, that reflects (at least American) society in general, where males are referred to by their last names among friends much more often than females.

[wvenable]

It also depends on the last name. Short last names will be used more than long ones, male or female. Funny last names more than non-funny ones.

[marblar]

Did you vote for Donald or Hillary?

[AareyBaba]

Bernie or Warren ?

[WillPostForFood]

It goes back to coaches using last names in sports practices. This probably is changing as there is more gender balance in youth sports.

[sixothree]

In the case of male Youtube makers, I find lack of any name whatsoever is more likely the case.