I think people should split up not only regarding to gear but also regarding to build.
Because while grouping up with my Pelta3>Matador2 is great since he’s got Swash Buckling level 15 to mob a whole room, my Kabbalist simply can’t do so, so if other people are interfering with me mobbing monsters, it will take a lot longer to have all mobs killed, especially if people are pulling away monsters once they move to not get hit.
But yeah, basically people should take a look at the weapon of the people and the Classes/builds at the beginning and act accordingly for the best possible outcome.
And of course they should start to learn what debuff skills like Double Chance or Geburah do to not interrupt/intervene with people doing fine [meh, that’s happening too often, with Cryomancers suddenly popping a Pillar behind you to take away all your mobs or some Peltasta using a lowlevel Swash Buckling on the move provoking away half of your mob, not to forget those autoattackers who blindly run through the room attacking everything…].
So, best is to not interfere with other people, if they split up at the beginning to go alone, let them go alone, it doesn’t really matter if they have the confidence to go solo and don’t make it, every mob killed efficiently is time saved for the group and if you make a round trip either way you’ll sooner or later meet up again.
Chances are that grouping up with them will hinder their gameplay, annoy them or and/or even result in your team taking longer because you did something unneccessary.
Also, damn those people not searching for left-over monsters who’re camping the boss monster warp once you’re at 97%+ clear. It just takes longer if they can’t kill the boss monster in 5 seconds once the dungeon is 100% cleared and instead pull it away to some random position on the map.