I love merc. mosh pit! It's great because I don't get trampled on by a full team, and any friends that do decide to join my session in progress might end up on the other team for a good challenge! One thing you can't do is unlock objective achievements for the calling cards of specific game modes, since the game modes are random.
Dont recreate threads, especially something like this. Merc has been around for what 5 games now? People know. There are better playlists for solo players.
This ^^^ If you have another thread that is getting swamped as you put it, you should bump that one and delete this one. No point in creating two identical threads.