I think they were trying to stop resellers price gouging during the chip shortage crisis. On ebay you could buy Pis for well over what they were available for on first-party sites (just like PlayStation 5s!).

As a counterpoint, they let me buy Pis as an individual, but I had to send in a picture of myself with a dated piece of paper like a Reddit AMA to prove I was legit.

FWIW there are Pi alternatives without the branding, but usually for the super low price point mini-PCs you are after you need to go to China to firms like Beelink...