The bolded is the important part. I've never realized this before, but this is one of the best arguments against Froslass, and I am surprised no one realized it, or realized it but never brought it up. Froslass centralizes the entire lead slot. If you aren't running a Froslass lead, you are forced to run Kabutops, Armaldo, Cloyster, Sneasel, Spiritomb, or anything else with Taunt that outspeeds. If you don't, you're risking having spikes set up in your face. (I'm guessing this has been brought up and I missed it, but in case it hasn't, I want to point it out.)
So... if you don't want to use Froslass, there are a number of options you can use to stop it from setting up Spikes, but because it forces you to use one of these so-called "counters"/"checks", and without them, it will get Spikes, it's broken...? Yeah, that argument wasn't brought up probably because that's not very good. If you want to make sure you beat something, you have to have at least a check for it. If you don't, you're doing so at you're own risk. When there are numerous checks/counters available, you can't just ignore them all, screaming that the Pokemon forces you to be... gasp... prepared for it by using them.
Under this logic, we'd have to send Aerodactyl to Ubers. After all, the only things that can stop it from actually doing its job and setting up Stealth Rock are Electrode, and risking a speed-tie by using Aerodactyl yourself. Since apparently five other options aren't enough in the case of Froslass, then only one other option definitely wouldn't be enough to keep Aerodactyl from being broken, so it should get the boot.
But once it's gone, we have another problem in the OU lead metagame: Azelf. With Aero gone, you're again stuck with two primary options for the lead slot: Electrode and Azelf. Look's like it's getting the boot too.
After that, where does that leave us... Jirachi? Uxie? Yeah, you get the gist. Quite obviously, from that it's been established that a Pokemon's ability to successfully get up Entry Hazards doesn't make it broken, or else we would have banned a huge chunk of the more common leads inn OU.
That is... unless you want to make the case that getting Stealth Rock up reliably isn't broken, but the ability to get up multiple layers of Spikes reliably is. In which case, you're left with two options: 1.) Ban Spikes themselves under the Support Characteristic 2.) Ban Frosslass under the support characteristic for being able to get up multiple layers of Spikes much easier than practically anything else in the lead metagame. Between the two, option #2 definitely does seem to be the better bet, as, at least for now, no other Spiker seems to be as good as Froslass, so option #1 would probably be a hard one to sell.
In any case though, that would be banning Froslass because it can, against a number of opponents, reliably get up multiple layers of Spikes, while also, due to its typing, making it difficult for the foe to Spin these Spikes away. Froslass "centralizing the lead metagame" by forcing you to carry some of a number of answers to it? Yeah.... not so much, as that comes off sounding like there are indeed answers to it, but you just don't want to change you're team to deal with Froslass at all and refuse to use any of them, which would be your problem, and not one with Froslass itself.
If it actually does very reliably get up Spikes and make it hard to remove them, then just say that, but, if I were to vote in BL, I definitely wouldn't say in my paragraphs that it centralizes the lead metagame by making me choose from one of like five leads if I want to beat it. As my point is that it's hard to get past it, I'd want to say that it's very difficult for any one Pokemon in the lead metagame to stop it from setting up Spikes, not fall prey to one of Froslass's other options, and kill it/prevent it from switching out so that it can put up Spikes/Spin-block later on, and its these combination of aspects that makes Froslass BL under the Support Characteristic. Just saying, or even mentioning the fact that it seems to be centralizing the lead metagame, makes it sound at least to me that you just want it gone and don't want to deal with it moreso than anything, so if it were me, I'd just leave that out and not bother with it at all, as I'm pretty sure that argument wouldn't help me and could in fact hurt me, and that's why I'm guessing most people haven't mentioned that: it doesn't really help their case much and they don't need it to support the case that Froslass is BL anyway.