I think you're missing the point, ropetight. Your example of a fighter with 20 Strength and 3 Constitution shouldn't even be possible, that is at least to be an adventurer. While technically possible in the rules, such a being would be monstrously muscled, but so ill of body as to not be able to get out of bed and support his own weight. Any RPG that would allow such a character to enter its game world is internally inconsistent. No competent DM would allow it, either, because that character would be a waste of everyone's time.
If a computer RPG allows such a character, especially to somehow be able to succeed despite the apparent lack of logic of its existence, then that character's player is min/maxing and thus, in a sense, "cheating".
Final thought, however: I don't think those who accept min/maxing will ever agree with those who dislike it. The two sides are far too dug in.