Your argument is somewhat plausible at first glance, but in reality it doesn't hold much water IMO. For the most, Crobat wasn't deemed broken for the fact that it couldn't be exploited by strong Rock/Steel types. Magneton and, guess who, Rhydon could already do that quite well when Crobat was allowed, but it didn't change the fact that they were overall inferior choices for the metagame they had to compete in, as the usage statistics proved.Also:
People probably haven't been thinking of this yet, but it just crossed my mind.
If Rhyperior comes into UU, I'm pretty sure Crobat and Staraptor will BOTH be far from broken. Giving Rhyperior a free attack = terrifying. Hell, even giving Rhyhorn a free attack = scary.
Not to mention people overlook the fact that Rhyperior isn't Dugtrio bait, due to Solid Rock and defenses.
So, if Rhyperior does drop down, that's something to look for.
As for Staraptor, it is true that Rhyperior has a better chance of taking it on than anything else likely to enter UU in the future, and could make a great check to SubRoost with Rock Blast and/or Roar, but really I don't think it would change the overall perception that Staraptor is frighteningly overpowering for the vast majority of the metagame. After all, besides Solid Rock, everything Rhyperior can do, Rhydon can do almost equally well, as there is very little difference stat-wise. Rhyperior would still have a hell of a time breaking through standard Milotic, for example.
@ Miltank talk: I think Kangaskhan does the Scrappy thing much better in this metagame, so Miltank is far better off using its other amazing ability to stand out. For example, Moltres is way too common a threat to pass up Thick Fat IMO, and reliable counters to that beast are few and far between. That's how I justify it anyway lol. Most people might disagree, but then again I don't see any of the really good players (those that don't just blindly copy from the analysis) use Miltank much if at all anyway.