I don't think your example here makes any sense. For one, the concept of "UU" is entirely online-based, IMO--there is no basis for UU "in-anime" as you put it. Barring the super-ancient legendaries which govern time, space, land, sea, etc, any Pokemon is as good as any other. If I may resort to Ash Ketchum as an example, he uses Glalie, Torkoal, and Swellow in what we see as in-anime high-level competition just as he uses Snorlax, Heracross, and Donphan. Secondly, the "in-anime" precedent is decidedly in favor of NFEs, despite your logic to the contrary. Thus, I agree with you that "allowing Monferno in UU" does NOT make any sense in-anime -- because "UU" does NOT make any sense in-anime.
Secondly, Ash uses a ridiculous amount of NFEs, again, in high-level competition. Squirtle and Bulbasaur have not evolved since the days of the RBY episodes, despite the fact that by your logic, "you would never use Squirtle when you could use Blastoise." And yet, to my knowledge, Ash has used Squirtle in gym battles and league matches (or, to put it another way, he does not discriminate by evolution status). The anime also goes to great lengths to imply that a fully-evolved Pokemon is not necessarily superior than its basic form, showing us evenly-matched battles between Piplup and Empoleon, Croagunk vs. Toxicroak, Pikachu vs. Raichu (before the advent of Light Ball), etc. Finally, the new D/P rival Paul is exactly an example of the mentality which you espouse, and he is unfavorably presented. Paul catches multiple Starlies, releasing the weakest; he also treats his Pokemon based on their performance and power. As a trainer, however, he is unsympathetic and reviled.
So what this boils down to is the fact that "in-anime" precedent absolutely does not support banning NFEs from UU, nor should in-anime precedent really hold any sway over any competitive rules, IMO.
edit - In writing this, I just remembered that they don't even SWITCH in-anime. Surely you can't really compare that to ShoddyBattle?