Interesting to me in that I haven't run into any issues, myself. Friends with Schwab and Fidelity had a completely different experience---were told what they could or could not buy. I wouldn't put up with that---I decide how to spend my money. I have a friend who is unable to purchase ERBB at his brokerage. I told him he needs to switch brokerages.
It looks to me as though some brokerages are more concerned with their in-house safety measures than focusing on customer needs and wishes. However, they are certainly entitled to their own interpretations of things. In the end, the process may enrich all of us. I hope so!
My opinions herein.