You've got some good responses here with respect to how it all works. I'll try to give an idea why at least in my opinion those of us our our side (sanity and free markets) are pissed. With respect to what's happening to the stock price it's all legal and I think most of us were just laughing.

But now, you've got trading platforms just straight up restricting transactions because they want to. Not because the SEC or the law tells them to, but to save their friends or side investments. Robinhood and TD Ameritrade are the ones getting the press for doing this.

There are reasonable restrictions a brokerage could do examples:

• Restrict buys on margin. Margin is credit you get from the brokerage, it's their money if they don't want you to buy these with that, then I'm fine with that. There are risk management teams and such at these brokerages that deal with margin accounts.
• Not be able to complete short sales. Short sales are selling stocks by borrowing them with the promise you will return them later under certain terms. If you can't borrow them, then it's a naked short (illegal). If the brokerage doesn't have any borrowable shares available, then it's reasonable for them to not complete a short order.

Then we have the unreasonable stuff, the main one being like what I'm hearing about Robinhood, in that for these certain stocks (e.g. GME) you can only sell them. They are just straight up not processing anything but sales. I'm not sure it's legal in the pre-one-party state sense. That's not to say that any order you put in is guaranteed to be filled, but you know allow the order. In a general sense a common market order for quantities most of us would be dealing with will get filled. If you do limit orders like I usually do, as soon as the Bid or Ask with enough quantity hits your limit price, you expect it to get filled.

A brokerage telling me they have decided they will not process legal orders as I have written them is one that would be losing my business. It's just way too much of a slippery slope. What happens when there's a huge drop and I want to sell on the way down, or more like me I want to buy some stuff after the huge drop for bargain prices, and they tell me "nah, we've decided you can't place that order because it doesn't benefit us"?