People are bad at this game

[Viridiana]

I think the restriction means you cannot enter below that level because most probably you would make the group wipe (that is, just one player under that ilevel would probably make the fight too difficult to win reasonably.) This does not mean that a group composed with everybody at the minimum ilevel would be expected to win, but rather than a group with only one player at the minimum ilevel, if the rest are not, can be expected to win if played reasonably well enough.

I'm confident in saying that the dungeons/trials are winnable with the party at the minimum ilvl.