Iron Crow suffers a lot to make a set, it is not considered broken. Defensive Pokémon like Tytar or Slowking manage to paralyze it almost without problems, allowing a moderately fast Pokémon to finish it off later. even without needing that, Lokix can OHKO him with First Imprision if he has the necessary damage, Ogerpon with Tera can lock him in calm mind using Encore, he may have to face an unaware skeledirge, etc. and this is not even close to all the risks that Iron Crown gets in the meta. eventually it works, but by practically only having one functional set, losing because of iron crow ends up being the player's fault, by not building things against / not protecting their wincon.
Kommo-o doesn't look broken, which is annoying. It has at least five different sets and you never know what you're going to find.