Google and Facebook both have incentives to turn "browsing the web generally" into "interacting with their properties specifically", so that they can capture your eyeballs. They both continually extend into areas that seek to replace large swathes of the web with interactions within their walled gardens, so that they can then monetize those interactions.
(Amazon has this incentive too, but they're just kind of incompetent at the execution, so people don't worry as much about them. See: the Kindle Fire tablet.)
Meanwhile, Microsoft doesn't currently own any property that operates by trying to replace "eyeballs on the web generally" with "eyeballs on that property specifically" to then sell those eyeballs to advertisers. They have Bing, Cortana, GitHub, Skype, maybe TikTok soon. None of those things will really change that stance. They're not "against" the web.
Apple is in the middle on this spectrum. Apple doesn't make money off web eyeballs, but they do make money off native app eyeballs (iAds), and also off native-app sales generally. So they're motivated-enough in providing a decent web experience to be the main sponsors of the WebKit FOSS project; but they're also motivated to create APIs that allow their third-party devs to replace web experiences with native app experiences.
Why? They’re more supportive of open source than they were in 2001, yes. But Google and Facebook are also big in this area.
And MS business still relays a lot on vendor lock in to a great extent