The loot system more than anything else seems to be what will push this more towards a large-scale LS event rather than a VW-styled PUG event.

It's also notably different from a Abyssea pick-up group setting, since at least in Abyssea you have the option to kick someone who lots something they're not supposed to. For Legion, once you're in, you can lot whatever you want, for as long as you're in the zone.

So yeah. Given the fact that most people in the game now have 5+ jobs they want to have geared at all times, and often considerably more that they play on at least a casual basis, having some sort of system in place to regulate who gets what is going to be nearly a necessity.

Unless, of course, the content is very carefully scaled and a small group of 4-6 can kill just as many monsters as a group of 36. Which, to be honest, I find highly unlikely.