Level 30~+'s In Abyssea????

Ok, so a week ago my LS went into abyssea to exp, and while we were in there we noticed that there was a few people from lv30-60 in there. A 35 BRD, 43 NIN, and some other jobs. About a 3 hours later, the bard was a level 55, NIN a level 58.
O_o. So I'm guessing that they were in a party with a bunch of other level 75+'s and just leeching off of them from exp from the chests? Idk if their exp would be gimped because they're a lower level, or if it would be the same. Would it gimp the higher level's exp?

Discuss O-o