When I make friends in a game, I want to play with them. If they're not on, but I still want to progress, what should I do?
I could hope that enough people are online on my server so I can form a group. This used to be the method, but was rejected.
I could play with people from other servers who I will never see again. This is the current method.
I could play with bots, which, if we given them a slightly randomized AI and name generation are functionally identical in all positive aspects to the people from other servers. I will never play with them again. I will develop no ties to them, because I will never see them again.
There is a benefit to bots. A social benefit, in fact. Since I likely have no concern for the random players, I am likely to treat them worse than I would friends or same-server players. Not with cruelty, but you cannot expect generosity in this situation. I have every incentive to take all I can, without regard for their needs or desires.
If they are already dehumanized, why not replace them with non-humans and minimize the damage inflicted upon the helpless other?
P.S. I'd rather play with the friends I made from the first scenario.