Devil's advocacy is about finding arguments for a given conclusion, including fallacious but convincing ones.
But what if you steelman devil's advocacy to exclude fallacious but convincing arguments?
Then the main problem is that it produces (and exercises the skill of producing) arguments that are filtered evidence in the direction of the predefined conclusion, instead of well-calibrated consideration of the question on which the conclusion is one position.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.