I installed, I uninstalled. Too bad is MMO, contents are blocked if not in groups
eh? i don't play the game anymore, and unless there's been some changes since i stopped playing but which content(s) is blocked? all game mode modes should be accessible (except those in the paid season DLC). even loot, all are RNG and can be earned from the usual daily and weekly grind.
only raids and the PvP gauntlet will really need you to be in a group to have _better success_ at completion. but i know of raid groups that are made up of PUGs and have completed (even better than pre-made groups).
as mentioned earlier, the only real content that is blocked is the paid season DLCs. base game should still have plenty to do including the single-player story mode. and can try out which class / Guardian suits your playstyle.