Feelings of injustice run hot, but the rules are the rules, and it was following the rules that resulted in the effects you describe. The rules even make sense, which I know doesn't help those that assumed they would face no obstacles while trading.
>>> The illegal practice of trading on the stock exchange to one's own advantage through having access to confidential information.
These guys had access to confidential information, and they prevented trading, and allowed specific trading that was to their own advantage.
This is a near textbook example of insider trading except that it wasn't the CEO who directly made the advantageous trades. But that makes no difference. This activity fits both the definition and the spirit of insider trading.
You can't say this is insider trading unless you generously expand the definition of insider trading to include every kind of wrongdoing in the market. Robinhood executives didn't trade GME and didn't have any nonpublic information.
These definitions matter.
So...not "nearly exactly" at all. Moreover Robinhood isn't even an insider with respect to GME.
No it didn't, because it didn't have privileged information about the securities. Just because it's a broker doesn't mean it has privileged information about the securities it brokers. Brokers do not typically have privileged information about the securities they broker. To have privileged information, Robinhood would need to be an insider to those securities. Which it isn't.
I don't know what else to tell you - your understanding of the conditions required to meet the SEC's definition of insider trading is simply incorrect. You need to revisit the specific definitions of "insider" and its impact on confidentiality and fiduciary duty.