No, it does not make it crazy. 2HKO on Corv isn't something new or special.For example:It DOES make it crazy, though. Please go into the calculator and do the math yourself to check it out.
Roaring Moon becomes an unstoppable wallbreaker with its base 139 attack. There are plenty of other things that hit even harder, or things that hit almost as hard and still do the job.
Let's take Brute Bonnet just to be absolutely hilarious about this.
252+ Atk Choice Band Brute Bonnet Crunch vs. 252 HP / 252+ Def Corviknight: 198-234 (49.5 - 58.5%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
And yes, it DOES outspeed Corviknight if it invests and Corviknight doesn't. And Corviknight would no longer even be able to tera Fighting/Fairy to resist and threaten to KO with Body Press.
252 Atk Choice Band Terrakion Close Combat vs. 252 HP / 252+ Def Corviknight: 204-241 (51 - 60.2%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
You don't even need Terra to do this in past gens.
Corv doesn't need to be able to wall every Mon in the game for the meta to be balanced.