>>39920937Swagger adds an additional layer of RNG onto a game which already suffers from it between accuracy, crits, secondary effects, etc. Not to mention in Swagger's case specifically you really can just outright die if you fail the coin flip.
Stealth Rock is powerful but it's also consistent. You know the rocks are there, you know exactly when they'll damage you, and you even know exactly how much damage they'll do.
There's a difference between strong and uncompetitive. This is precisely why Lando is OU and yet Aegislash is banned. The former is just strong, whereas the latter is literally a guessing game where you die if you guess wrong.