The entire point of this idea is to give people the option to keep working on gear should they wish without requiring them to. It also gives players such as myself a way to burn through the massive amounts of rarities that I have while also having more fun fighting T4 enemies.

If T4 enemies were to take a page out of the rest of the game where they have unique attack patterns and new abilities instead of just being tankier versions of the current tier 3 enemies I'd definitely enjoy them more. However, that being said, I don't particularly enjoy fighting T3 enemies with T2 gear, which is what we currently are emulating by fighting T4 enemies with T3 gear. It's not impossible, but it's not exactly more challenging so much as makes engagements last longer.

Just like how you don't necessarily need to bring 4* or 5* gear into tier 3 to complete it, you wouldn't need to level gear up using this system. I'd imagine it would be a gradual scaling as well instead of being an instantaneous upgrade like most tier jumps are, but at the very least it lets the player pick and choose their favorite gear and level them up to take on the hardest parts of the game. In doing this, gear that is viewed as typically underpowered may have the opportunity to be on equal footing as top-tier weaponry without upsetting the balance in lower tiers.