One could argue that Hitler was at least competent.
That is a fascinating argument for two reasons I can articulate.
1) Was he really so? I will not look at his prewar performance, on the general principle that war is the test that has mattered, perhaps until now and in general.
Looking at his wartime record, he made a number of truly bad decisions: operation Barbarossa, fucking with Rommel, misusing air power. He nixed a big bomber ... and then decreed that the jet engine be used poorly. Other examples abound, but this is not an alt-hist forum.
So I contend he failed the competency in the Final Jeopardy round.
B) The other, and this is imo the big one, is what your brief comment implies. It is the oddly Calvinist notion that success equates to moral goodness: "might makes right". This is a common human reaction and one that I have seen used as a "wedge" to legitimize some of the more unsavory deeds by powerful people.
Does Hitler's having done some great things (economic recovery in Germany, those roads, the finest war machine on the planet) justify, mitigate, forgive ... his obvious atrocities (nine million dead, of which only six now get much press, and the scary thing is he sold it as Necessary)?
I contend that the answer is No. The difference between principle and pure predatory thinking (as codified e.g. by Macchiavelli) is codified by the question of the end justifying the means. This is the hinge of principled society ... that we recognize universally-observed limits on what we do. I think it is fundamentally evil to do what we want ... and then use our single or massed intellects to sell it as moral right or necessity. This leads to an entire generation of people who grew up with such a cognitive disconnect that the propagation of logically fallacious but populistic arguments are easy to instill and propagate. It makes us weak ... which ultimately leads us to fail the Calvinistic function test, whose pinnacle is performance in total war.
Thus I see two problems with the idea you suggest. Ultimately both boil down to the idea that the implied evolutionary advantage does not apply.