I feel it adds a lovely bit of variety to the experiences. Tried a journaling RPG for the first time recently — spending 4 hours imagining experiences, describing them, and guiding my creativity with the game's ruleset / prompts. The game allowed room for introspection, for overcoming internal obstacles, for writing / thinking carefully about how I phrase things.

That was a profoundly different experience from my Tuesday afternoon RPG campaign where the social aspect, on-the-fly improvisation, "yes, and"-ing and the collective storytelling dominate, but would not discard the solo game as a bad idea — it's just built for something else.