To be fair:
The fifth generation Apple TV device is officially called Apple TV 4K so it has a slightly more distinct name than this article implies
The fourth generation Apple TV device (the first one that can run tvOS) has been retronymed Apple TV HD for about a year now. Granted, it's not the first one that can do HD content but as of right now if you try and go buy it on Apple's site it's called Apple TV HD.
The third generation Apple TV device and prior were indeed just called Apple TV but Apple doesn't sell them anymore although slightly confusingly the third generation Apple TV can actually be updated and subscribe to Apple TV+. Not sure what you use it for.
It's true Apple does get confusing with their names, usually using some combination of "iTunes", "iCloud" and "Apple (other word)" but they at least tried to lessen the impact of this a while ago with their own hockey puck device.