i think it’s entirely the matchmaking system, owing the hundreds of discrete PSN folks I’ve played with/against. I play most of the time by matching up through the chat/lobby, but a decent chunk of the time, i will just drop into a “standard” match when i only have time for a few matches, and almost always find humans in those as well.
The chat organized matches are rarely less than 6 v 6 (humans) and are often full… and the standard matches are often at least 3-4 humans per team, or get that way after a round or so. (i’ve dropped into a standard match to test a new ability, been the only human at the start, and by the end of the match, it was 3-4 vs 3-4 (plus bots).
one problem (still, as always) is when you start a match and are the only human, if you back out right away (and everyone else is doing this too, no one finds each other). if you get a match going, people who are dropping in are more likely to find your match, vice versa, etc.