That also gives much more experience and makes leveling up throughout normal mode (and nightmare with some characters) very easy, it even increases drops too so farming runes for op runewords is actually easier on a higher player setting, when all you gotta do is teleport (can buy staffs that let any character use it with charges, or find amulets that do the same) in and open all the super chests in lower kurast in hell difficulty for that.
The difficulty being lowered for ubers in mods i was refering to is that they don't summon actually summon their minions, which makes killing the ubers in single player mods rather easier since the minions won't get in the way to let ubers recover health quickly
I'd say the xplayers is more helpful then challenging with speeding up the early game grind and in the late game when hunting for items, but yeah, players 8 does make it alot harder for one character in particular, which is the necromancer. corpse explosions Life% damage is based off the players 1 health settings so it does almost no damage anymore to the /8 ones at that point and that's his main spell for clearing throughout the game.