No, it doesn't. But neither does it take less skill. You need 3 or 4 people to be collectively more skillfull then opposing team. And it does not just mean four better 1v1 players. You often need different skills in 1v1 and in 4v4. Some players love to be a solo hero, others prefer team play.
This
There is no inherent reason why 4v4 should be less skilled than 1v1
However the skills that you use for 1v1 are much more useful to 4v4 than vice versa
Further, most of the best players play 1v1 and 2v2
Therefore the best 1v1 player is probably better than the best 4v4 player, and his micro skills will serve him better in 4v4 than the 4v4 guys macro skills will in 1v1.
BO may have to be adapted though because of the greater variety of oppossing units and abiliites he will face.
Snipers for example are good 1v1 but less seen 4v4, this is one reason why long 4v4s turn into tank battles because everything else dies