People on Xbone must pay for Xbox Live gold to play multiplayer on this game via Xbox Live, yet people on Windows 10 can play on Xbox Live for free?
I find that unlikely.
Then you continue to not listen.
Online Multiplayer is
NOT the main service provided by Microsoft when you purchase Xbox Live Gold. Microsoft don't even host servers for games, and expect the developers to do that themselves (Note: It's more complex than that, but the jist of it is that Microsoft really isn't doing much for online multiplayer). It is simply a paywall to convince users to purchase their subscription service, and they then offer the other benefits which are actually beneficial and probably cost Microsoft a bit every year.
People on Windows 10 won't have Xbox Apps because it's a free environment, and people would be using their own different services and applications. Unlike the Xbox, it's not a controlled environment, so Microsoft can't entice users to purchase Gold since they can't offer anything to gamers that we don't already have or have alternatives to. And since Windows 10 will not offer support for every Xbox game, they can't offer us free games either.
It would be a stupid move if Microsoft made this shared multiplayer feature one that requires a subscription by people who are using Windows and won't be able to access the benefits.
Stop acting jealous that PC gaming isn't controlled by Microrichards.