It's because of the price. IMy budget is 2K and I can get the LG OLED for 55 C7.
But yeah, I wish the price of the 65 OLED was better... Outside my realm right now.
For the OS. I don't use it and won't use it much. I have an Nvidia Shield TV that does everything media related for me + game streaming.
The 65" B7A (and maybe the B7 and C7) should hit $2k at least once this holiday season. If you can wait a month and change until Thanksgiving weekend you can probably have a 65" OLED for what you'll pay for a mid-range Sony LCD now. Or, if you want an LCD, there may be sales that allow you to move up in range on the Sony LCDs.