The discussion was about M$ Store, not win10. Yes, win10 is a pain in the butt, but there are plenty of people who would prefer steam version of the game even though they have win10 already installed. Most cite convinience of having games in one place and M$ Store being generally not very intuitive and useful as their reasons.
The only upside of M$ Store, which is the xbox integration, is pretty much useless for rts players, as many of them don't own any consoles either way.
Being exclusive reduces audience among win10 users as well, even if they don't have to face as many new problems when they decide to get the game either way.
Let me quickly elaborate then:
Steam isn't very welcoming for games that require very specific OS to function, that is why there simply aren't any, maybe except one or two.
MS however enforces use of DX12 for the games they publish to accomplish couple of goals
-first is the traditional, binding you to inferior platform that isn't steam
-second is to push people to upgrade to win10(since that's still free and permanent)
-third is more of a bonus you've mentioned, xbox integration and crossplay for some titles
MS doesn't need or want successful and great games, they want excellent marketing tool to make more people move to win10.
Now, regarding RTS, there is Halo Wars 2, which apparently is pretty good, successful, operates on crossplay and isn't dead yet, don't know, just played a demo and it was alright.
Relic Entertainment
