That idea would be great, if individual Linkshells didn't cap at 150 or whatever the number is. Hardly enough to accommodate an entire server. If this were a real possibility, I wouldn't have even entertained this idea, really.

There have been many all-inclusive shells out there that have come and gone since launch. At least with this system, it's impartial to the game's restrictions, and although moderately cumbersome to use, is totally membership cap-free. They will soon be implementing a party-flag feature similar to what we had in FFXI (icon beside your name).