You could just not use Duty Finder? I always see this complaining that people don't like what they get but they never take the opportunity to make their own group with people they can know before entering. I admit people do enter dungeons under geared sometimes however that's the risk you take. If you don't want to take the risk, plan it out before hand and get a group together that meets your demands rather than placing a restriction on everyone simply based on their weapon.

If I wanted to farm good gear before even trying ifrit etc to make sure I was good, farmed a full set of AF2 but still had a weapon of say item level 49, does that mean I'm not a good enough tank for Ifrit? If it was considering all gear I would still be against it because this way promotes people to make their own skilled groups if they get fed up enough. Hopefully people will realise this and keep their elitist views away from the general community and in their own community entirely, that way people would be a lot happier playing their own style.