Re: You now see where the revenue stream is
"what is to prevent Microsoft from blocking all programs that are not installed using their store?"
Well nothing, if they think that's what their customers want. Just like there's nothing preventing them making it compulsory to repeat "All hail the mighty Gods of Redmond. I pledge my allegiance to thee!" before it will allow you to log in. They produce the OS, they can make it behave exactly like they want.
But it's not going to happen, is it? Because customers don't want it and it would be illegal to boot. That's why no OS and no company operates this policy. I know constructing nightmare scenarios are fun, but time to take off the tinfoil hat and rejoin reality.