I think Trollsmyth has mentioned that the solo game didn't start out that way. Originally we had four players, then lost two, then the third, added another who only lasted one session, and so on, until the group finally settled down into me, and some NPCs who I pretty much treated as members of the party. Whether it was just schedule problems, or a side-effect of chat gaming, or Trollsmyth's peculiar campaign style I couldn't say, but lately the group game has been having similar trouble. We're down to just me and the boytoy, from a group of four players, and while there was an extended attempt to add a third player it doesn't look like the schedule is going to work out for a while.
Which, honestly, may be okay. I liked the other characters when they were around, and that potential third player would have been a lot of fun, but having just few players has some advantages. He and I have built a rapport, our characters don't get along in all kinds of fun ways, and it means the NPCs in the party get a lot more screen time. Since they interest me (and boytoy has amused himself by finding various ways to make their lives miserable) that's been working out well.
As a general rule, I'm coming to prefer solo and small-group gaming. One, two, and three people means the game can be more character driven, more interaction-focused, and more responsive to the specific things that I like, with fewer player agendas to juggle.
Which is a bit different than the freewheeling, "whoever shows up can play," megadungeon and wilderness crawl kind of play that I think of as quintessentially "old school." I suspect that those kinds of sprawling campaigns played a significant role in creating and anchoring communities of gamers, and I would like to run or play in such a campaign at some point, but mostly for the novelty of it, and to better understand how such things function. My real interest lies in smaller, more focused games.