There are measures in place to ensure that you can upgrade your gear to a certain point regardless of RNG. The soldiery and poetics points. You also always have the option to buy/craft gear as well (although that's quite expensive or time consuming at high level). But the point is, a person can be well geared even if they were to never get a single dungeon drop.
A person can never upgrade their weapon past the atma step if the RNG is pissing on them.