It's fine for Microsoft to push SOD2, or any game that might review in the 70s, as a tentpole release. It might not be for everyone but it's had a lot of positive reviews too. See also Gran Turismo Sport that sits at a very similar Metacritic score to SOD2 (75%). That's positioned as a tent pole PS4 exclusive and many claim it's the greatest racing game of the generation. Im sure Hyrule Warriors will be pushed by Nintendo this summer as a big exclusive and it's currently sitting at 77%, very similar to SOD2. A lot of people here love Hyrule Warriors. It's reviews. I'm sure, just like the first game that reviewed in the 70s, State of Decay 2 will find a very passionate and loving fan base.
Hyrule Warriors is a perfect example though. If the Switch hadn't had a great recent history of exclusives, and there were no promising upcoming exclusives on the horizon, Hyrule Warriors reviewing sub 80 would be far worse for Nintendo, as there'd be much more resting on this game's critical and commercial success.
Nintendo is in the comfortable position of being able to treat HW as a "people who love musou games are going to have a great time, it's a somewhat niche game" thing, Microsoft isn't in this position.
A PS4 70ish% game is a "good" game but an Xbox One 70ish% game is a "blunder". Come on man...
Don't try to make this a fanboy thing. I consider both "good" games and both "blunders" at the same time. But to miss 2 out of 3 is certainly a
bigger issue than to miss 1 out of like ... 8? Especially when you're in dire need of good arguments against the narrative of "Xbox got no good exclusives".
That might all change when MS reveals new upcoming titles at E3, but right now - what is there, other than Crackdown 3?