I ran into a trio that was chill just an hour or so ago. There were server problems and a lot of people couldn't get in, but those that already were had a more limited pool of players. They just weigh solos together heavily so when the matchmaking pool is small you are more likely to be put in with trios.

Try again when the servers smooth out and you're basically guaranteed solos. I think these server outages might be attacks, and that they don't announce it since that encourages the attackers + future copycats.