In many ways, Traveller is the ultimate "lonely fun" RPG. Character gen, world gen, ship design: these can all be incredibly engrossing solo activities, and with the addition of various makers T5 is in some ways the apotheosis of these subsystems.
MgT 2e, in contrast, is very much in the modern spirit of being accessible and easy to run "out of the box."
An underlying premise to many of these discussions, and one that I reject, is that these "lonely fun" activities are somehow not really fun or less worthy than live game sessions.
Now, I love getting together with a group, I love interacting and being surprised by other players.
But I have also gotten a lot of enjoyment and satisfaction out of the solitary stuff, as well. I certainly would rather play around with worldgen than fiddle with some phone game.