You can make a solo FC, you just temporarily invite people to create the FC. You can buy a house on a full server, you just have to have a lot of gil and find someone willing to negotiate transfer, and get a GM involved to make sure the agreed upon price is not against the GM's interpretation of game rules and that one party does not cheat the other party. You can build an airship alone, you just need 3 other people in a party on any level crafter classes inside your workshop when you put in the materials, but you would need to meet the minimum level crafter/gatherer for each of the items you toss into the workshop.

I'm not saying the requirements to access airships are fair, but you are wrong when you keep saying impossibru this impossibru that.