I would invert the causality. Why would I spend six months outfitting a carrier if I had no intention of using it in combat or even flying it anywhere where other people would see it?

Same reason people spend hours tending their farmville farms...

I've never played Farmville, so I probably shouldn't speculate, but I'm under the impression that it is at least ostensibly a social game where you invite people to help with or at least view your farm.

Yeah, but so is EVE and other games like it. I have never played EVE for any significant amount of time, but I did play WoW for awhile and there were tons of things that people would sink time into for purely social reasons. I imagine EVE is the same way. You don't just want a Titan because it is useful in the game, you want a Titan so you can have a Titan.

It's more of a social ponzi scheme. The fun part is the very-passive, easy progress. You just click on things. When you get people to participate in your farm, you're just saving yourself lots of time and clicks.

Well, you wouldn't do it at all. That's why the alliances try to help their members after fights.

Maybe you just want to use it to pick off all the smaller guys. You enjoy driving it around and being the Big Man On Campus. But, you don't want to take it into a real fight, you might avoid an actual conflict with it.