Why did they all come to the same conclusion at the same time?
It's blatant protection for short positions. These brokers are hamming up the "we need to protect retail from volatility" narrative when they're clearly trying their best to stop their business partners from going bust.
It's sickening.
Let's be clear about a few things. Brokerages do not care about protecting retail investors, they only protect their customers when forced to do so by regulators. What brokerages do is protect themselves from liability, financial losses, and scrutiny. They have no problem screwing over their customers when it suits them. They will raise margin requirements and force customers to take a loss as soon as their risk models say that they should do so. They will restrict trading whenever it looks like there is a scam, simply because it wards off possible investigations into their business.
What they can get in trouble for, and RH did get a slap on the wrists for already, is working against their customers' interests for the benefit of their business partners. One brokerage I could believe, but I doubt that half a dozen would all do it at the same time and with the same securities.
I can see the nice narrative of allowing retailers to sell ("capture gains"), but it's indefensible to only allow selling.
That's _blatant_ market manipulation.
I'm not talking about edge cases with margin calls.
I want other examples where it's appropriate for some brokers to restrict _buying_ but not selling, especially in the context of a short squeeze, with potential conflicts of interest.
I understand that brokers can restrict trade on risky items as yes, it impacts their risk model. I'm failing to find justification for RH and others to restrict buying but not selling of GME.
Your first link is for penny stocks, and the restrictions revolve around the usual pump-and-dump. You're allowed to go long, and can trade between days.
Your second link is for OTC, and I fail to see how this is relevant to GME. GME is traded on formal exchanges, and brokers that haven't arbitrarily restricted buying aren't having any liquidity issues.