short answer yes long answer yeeeeessssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss serious answer is right here if you are actually tryhard enough to highlight this what n0thingspecial meant is that you either can't play anything below certain AR (mostly AR8.9 or below) or you can't even acc well below certain BPM (say, below 180 or even 160) so basically if any one of the condition is met, then you are already getting harmed by playing DT also, "too much" is really subjective considering that someone can play only DT for a whole month without losing any skill to play slow stuffs, and then there's me who get fucked by DT after an hour of playing
If you wanna play only DT, just keep playing DT only. Same goes for Hidden. Some people say you get worse at nomod if you play HD only but I don't see the issue. You are not forced to put off HD ever except for maybe tournaments or hosts that refuse to put freemod on.
Dunno about HR, I can't see how spamming HR on lower rank is fun.
Edit: Well, you can't put DT on in MP if you care about that, but if you just play SP then there's no reason to quit playing it / not play it all the time.