I know fascists do this, but doesn't everyone kind of? If you don't think your enemy has strengths then they're not worth being your enemy and if you don't think they have weaknesses then opposing them is pointless.
edit: I guess one difference is fascists pick enemies that genuinely are powerless, but that doesn't really seem to line up with the original claim
I think it's more just that it's a necessary rhetorical thing
Like your enemies have to be subhuman and pathetic, cos it defeats the purpose if they're actually superior to you (and strength ~= superiority in fashy thought)
But they also have to be an overwhelming threat to your way of life to justify what needs to be done