I can't see how ferrothorn centralizes the metagame around itself at all.
An offensive threat needs to be surmounted by whatever checks it. The check needs to be faster, hit harder or take hits better, trump it's type coverage and resistances... You need a specific pokemon to counter one offensive threat.
For example, eelektross is not a garchomp counter/check. It's not fast enough to outspeed garchomp and KO it with hp ice and it's not bulky enough to take an outrage. This illustrates the criteria of a successful offensive check.
But to check a defensive pokemon, what do you need? They're usually slow (very slow in FT's case) they don't hit too hard and use support moves. In ferrothorns case, it can:
Attack with a moderately powerful gyro ball or power whip which are both easily walled.
Set up spikes or SR which can be spun away.
Use thunder wave. Ground types and restalkers handle this.
Leech seed. Grass types, spinners, magic guarders, liquid oozers and pokes with low HP to lessen the return...
Taunt. Taunt shuts him down completely.
Ferrothorn has plenty of counters. Are taunters that resist steel & grass rare? How about grass types that resist SR and can heal status? There are so many ways to handle whatever ferrothorn does that, just by building a decent team, you can handle him easily.
All you need to stop him is a decently powerful fire/fighting attack. If you're smart your team will either resist hazards or have a spinner. When it walls something, you switch out of leech seed to nerf it's recovery.
And how does ferrothorn render certain pokemon unviable? I haven't seen any examples besides maybe swampert. Slowbro renders certain pokemon unviable too. This is called being outclassed. If you think that ferrothorn renders an offensive threat unviable you're wrong. I don't think that any pokemon can sweep while it's counters are alive. So what do you do? You KO the offensive pokemon's counters to clear the way for it to sweep. This happens all the time. Why does ferrothorn get special treatment? He's a prominent wall, so you run the fire/fighting moves to get rid of it. Not the unique NU otherwise deadweight counter. Almost anything can check ferrothorn if it has the coverage move. This is not overcentralizing.
Poliwrath is unviable until jellicent is Koed. You KO jellicent. You don't stop using poliwrath.
Ferrothorn is special, I think, because he's the only steel type in OU that resists water, grass and electric. He's a physically defensive steel type that has special bulk as well, and these resistances cover a gaping hole in the armor that most other steels have. Look at it this way:
What's wrong with forretress? He has no reliable recovery, bad STAB coverage and a lowish attack stat. His special defense is too low, and he doesn't resist water or electric, giving him a huge weakness on the special side.
Ferrothorn is forretress 2.0. Forretress with all the weak spots covered. Super forretress. He has higher attack and lower speed for gyro ball plus powerful grass STAB. He has high special defense and the resistances to wall special attackers just as well as physical ones. Leech seed gives him reliable recovery. It's like a new swampert with recover and sap sipper.
I realize that there are holes in all this, but I'm tired. I kinda rambled a little, but hopefully I got the point across.
An offensive threat needs to be surmounted by whatever checks it. The check needs to be faster, hit harder or take hits better, trump it's type coverage and resistances... You need a specific pokemon to counter one offensive threat.
For example, eelektross is not a garchomp counter/check. It's not fast enough to outspeed garchomp and KO it with hp ice and it's not bulky enough to take an outrage. This illustrates the criteria of a successful offensive check.
But to check a defensive pokemon, what do you need? They're usually slow (very slow in FT's case) they don't hit too hard and use support moves. In ferrothorns case, it can:
Attack with a moderately powerful gyro ball or power whip which are both easily walled.
Set up spikes or SR which can be spun away.
Use thunder wave. Ground types and restalkers handle this.
Leech seed. Grass types, spinners, magic guarders, liquid oozers and pokes with low HP to lessen the return...
Taunt. Taunt shuts him down completely.
Ferrothorn has plenty of counters. Are taunters that resist steel & grass rare? How about grass types that resist SR and can heal status? There are so many ways to handle whatever ferrothorn does that, just by building a decent team, you can handle him easily.
All you need to stop him is a decently powerful fire/fighting attack. If you're smart your team will either resist hazards or have a spinner. When it walls something, you switch out of leech seed to nerf it's recovery.
And how does ferrothorn render certain pokemon unviable? I haven't seen any examples besides maybe swampert. Slowbro renders certain pokemon unviable too. This is called being outclassed. If you think that ferrothorn renders an offensive threat unviable you're wrong. I don't think that any pokemon can sweep while it's counters are alive. So what do you do? You KO the offensive pokemon's counters to clear the way for it to sweep. This happens all the time. Why does ferrothorn get special treatment? He's a prominent wall, so you run the fire/fighting moves to get rid of it. Not the unique NU otherwise deadweight counter. Almost anything can check ferrothorn if it has the coverage move. This is not overcentralizing.
Poliwrath is unviable until jellicent is Koed. You KO jellicent. You don't stop using poliwrath.
Ferrothorn is special, I think, because he's the only steel type in OU that resists water, grass and electric. He's a physically defensive steel type that has special bulk as well, and these resistances cover a gaping hole in the armor that most other steels have. Look at it this way:
What's wrong with forretress? He has no reliable recovery, bad STAB coverage and a lowish attack stat. His special defense is too low, and he doesn't resist water or electric, giving him a huge weakness on the special side.
Ferrothorn is forretress 2.0. Forretress with all the weak spots covered. Super forretress. He has higher attack and lower speed for gyro ball plus powerful grass STAB. He has high special defense and the resistances to wall special attackers just as well as physical ones. Leech seed gives him reliable recovery. It's like a new swampert with recover and sap sipper.
I realize that there are holes in all this, but I'm tired. I kinda rambled a little, but hopefully I got the point across.