The item req level is probably the minimum that is theoretically possible, to be honest I have doubts about even that. In any case setting it that low is functionally useless because if someone scrapes in with that gear level they are certain to get carried, because your chances of a equally geared group clearing is something worthy of a youtube video like the 4 man titan HM.

The way item level should work is that it should be set at a level where you don't overgear any mechanics but you have at least some margin to be less than perfect, and disabled altogether with premades for groups who want to do some freakish feats.

It is not useful to say "it is possible to do it with this gear" and allow pug parties to form around that because there is a large gap between what is possible and what is reasonable. It is possible to climb Mount Everest but I'm not going to ask 8 people from a McDonalds drive thru to do it.