Everyone knows that.
Because MS pays them millions of dollars for exposition.
Only failed and indie games benefit from GP.
Most relevant studios and games don't need it.
And the same is true for PS+.
Big relevant studios don't need these subscriptions services.
Facts.
If you're game failed to meet expectations but got better, like recently guardians, then putting it on a service is a nice way of getting money upfront, and drumming up excitement.