I don't understand. How is it cheating to order your discard pile if you also shuffle a sufficient amount to randomize your deck?
There are two environments to play in: ones where the players make the rules, and ones where some higher authority does. Let us refer to these two environments as "kitchen table" and "tournament." We could add "digital" as a third environment, but the shuffling is automatically good there, although I guess some people do blow it on that algorithm.
At the kitchen table, feel free to play whatever variants you want. If everyone agrees to the variant it's fine, if someone disagrees but someone else secretly does it anyway it's cheating. This seems really straightforward. You can all agree to sort your decks rather than shuffling them or whatever you like.
At a tournament, there are two problems with ordering your deck before shuffling thoroughly.
1. It's stalling. It's not okay if it has an effect on your randomizing, and if it has no effect it is an action with no effect that takes up time. We only have so much time for these tournament games. This, by itself, is enough to always prohibit it from all tournaments.
2. It's clear that you're trying to cheat. I mean get real. The entire point of the ordering is that it may help your draws. It doesn't matter if you then shuffle thoroughly; you don't get to try to cheat, just as you don't get to cheat. Trying to cheat, even with no chance of success, is itself cheating (a different kind of cheating, since you failed at the first kind). Similarly attempted murder is illegal even if no-one dies. wtf, right? I mean what if you just want to try but fail to kill someone because you're superstitious? Well local laws may vary.
We are not talking about sacrificing ducks; ordering your deck has a direct effect on the final order, even if you shuffle thoroughly, which sacrificing a duck does not. Sacrificing a duck would be way heavy stalling though.