This works up to a point, but once you hit a certain power threshold it seems like you can no longer stack enough modifiers to reach a C+ rank, which will then net tier 1 loot. You are right though at my current power level I [i]can[/i] stack enough modifiers to reach a tier 3, but stacking all the modifiers up on expert no longer nets me a tier 2, which would lead me to believe that sometime soon if I continue on my power climb tier 3s will no longer be accessible to me for the same reason. What happens if you try to load in to master activity with your 500 power warlock? Can you still get tier 3s? My issue isn't just the fact that I won't get loot of that tier anymore though, it's that I'm no longer to able to experience the content that I want to play at the difficulty that I want to play it at anymore and still get the rewards I would have received earlier in my power grind. For instance for me a master level strike at -30 power delta, maybe a couple of modifiers, is a great place to test out new builds and have a low-key run with friends. For me to play that now, I have to load up all the hardest modifiers that change the gameplay experience substantially (which I think is a separate but related problem). It kind of feels like I'm running a bastardized version of the content at that point. TLDR: At one point I was able to get consistent rewards for playing the game in the way that I liked, but now that my power is higher I've lost access to that experience because of that arbitrary number.

By that time your power is so high that 2 tiers below your max PL only gives T1 with max modifers you go up a tier and will be really really over leveled for that and still get your T3/T4.