Because companies decide what they want to distribute/sell to their clients. If not companies, then laws of the country you live in are above their company strategy.
Your head is twisted, a company is deciding what OTHER companies are allowed to sell BEYOND the laws that govern. It is blatant over-reach made worse by the fact that the open letter was drafted by a conservative think tank hanging over their shoulders. Literally pre-Gestapo shit.
Let me clarify, this is several companies deciding what other companies are letting OTHER companies letting OOTTHER people purchase. If that wasn't enough fucking redirect for you. So, tell me this is the fReR maRkEt one more fucking time.