It's not all that surprising:
1. It had the disadvantage of being a launch title that is available on another platform at the same time.
2. Despite have an extremely high attach rate, I believe the Switch sold out at around 2 million .
3. PlayStation having a large userbase isn't really a factor, but it kind of cancels out the new hardware launch
factor along with #1.
4. Speaking of #1, there are a lot who are waiting for the Cemu to either buy the game or pirate the ISO. One of
the main reasons the Cemu paetreon is getting such high "donations".
5. Horizon is actually a great game (Personally I don't think its for me, but watching my friend play it for a bit I feel
I can say its a good game.)
6. BotW is completely outshined by the most realistic looking and feeling game on the Switch, 1-2 Switch.
EDIT
7. And I guess Horizon came out earlier than BotW.
