Not trying to be rude or anything, just curious is you are aware of:

Minimum Item Level

Settings in duty finder?

It doesnt make it "harder" per say, since a lot of dungeons have been seriously lowered in difficulty such as Pharos Sirius, and Amdapor Keep for examples.

It does however lower your HP, defense, and damage etc. Basically akin to raising the enemies HP or damage output but the opposite, lowering yours.