But, there’s no difference in difficulty between NMD Tiers when you are able to pick the exact tier/difficulty that most closely represents your build efficacy/power lvl and your own comfort.
Developers knew this from Greater Rifts in D3, that’s why they introduced dungeon affixes in Nightmare Dungeons. Many players constantly complained about them though because apparently we can’t have anything challenging in this game.
If you enjoy them, don’t let me ruin it for you. But, don’t tell me I should enjoy them too. They’re not meant to be challenging or very engaging in any capacity. They’re mostly meant for speedruns and blasting.