I solo'ed my main job (Monk) all the way to 50. Aside from two levels I got in 1.0. It's easily do-able. I didn't have the story completed in 1.0 and I never unlocked a chocobo or a license in 1.0. I honestly just walked everywhere. When I started ARR I used porters to get everywhere and just walked. Well this past week I took my Lancer through the storyline and unlocked my license by getting 2,000 grand company seals. Easily done with doing Fates. It's easy. Solo'd it all except the needed dungeons. I used duty finder, got them over with and did everyone else alone. So yes! You can solo most of it, everything else is duty finder!