I think we are missing the point here. We aren't reading between the lines. And let's compare it to WoW. Not because it bothers you, but because WoW is a valid MMO to compare it to.

WoW is successful with the ability to solo to end game simply because of this;

You don't have to solo to end game. However, WoW has it on a much different level than FFXIV. For example, I can log into WoW do some solo questing or grinding to level my character. At the same time, I can also PvP, run dungeons, or gather materials to level.

It's not about playing with or without people. Its about playing how you want to play.

This game is not successful because it either IS or IS NOT solo capable to end game. It is not successful because all that you CAN do is leves which are on a cooldown or grind monsters. Its the lack of choices, or, basically, content that is killing this game right now.