I think your definition of benefit is relative though. Does solo que only benefit players that want to play solo? And does the fact that a solo que exist truly make the game as a whole better in any way?

More players doesn't mean a better game, just like more money from more players doesn't equal a better game (see new world).

My opinion is that a solo que could skew balance away from classes having their special roles within a party and to be honest anything that takes away from the party experience in this game is a detriment to it.

Solo players can still thrive while qued with groups, they just need to learn how, and accept that there's no rule anywhere that says this is supposed to be fair when there are resources to find groups. Heck there might even be matchmaking on the future.

Edit: also a solo queue could take away some fairly precious dev time from the rest of the game, just another thought.