I didn't respond to this so as not to get into it, but put simply, Devs promot grouping because you 'have' to promote grouping in its current implementation in order to get the community to ever do it. Grouping takes more time and effort to put together and go about your task then it does to run it solo, thus if people can solo, they will. There are those who always want to group, however having so many others soloing tends to leave them without members, which is the current danger to the current implementation of grouping/soloing.
Yes, I bolded those bits for a reason. Remove the time and effort from grouping, such as is done on rare occasions in different games and is done here in XIV by way of the Behests, and people will group or solo as they choose.
I say again... grouping is promoted because it 'must' be. What does that say to you?
Okay, now you're debating over semantics. This thread was started to discuss the aspect of running solo rather then grouping, which is the actual process of forming a party mechanic supported team. Nothing else is relevant.