These other companies may not always work together in harmony, but at least they aren't preoccupied with extinguishing their competitors and dominating ("owning") their users.
Microsoft is a special case because they had a zero-sum game/scorched Earth mindset, and the ability to lose billions of dollars per year, indefinitely, achieving it.
Microsoft was not content at allowing potential new ideas/technologies develop which might grow the market and improve things because they saw everything as a potential threat to their position. So they would do everything from trying to poison the market, to pouring (losing) tons of money into competing products, and sometimes just buying up companies and let it rot.
The very special part is as long as Windows and Office were cash cows, stock holders weren't willing to lead a revolt for Microsoft losing billions on everything else.
Not all companies are not scorched earth (SGI gave away serious resources to Nvidia, Valve recently gave away their VR tech in the highly publicized layoffs a few years ago).
Other companies might like to play scorched earth, but they don't have the ability to piss away money like Microsoft. This is why Microsoft is a special case.
Microsoft still has tons of cash and Windows/Office is still a cash cow. And it is generally accepted that company culture is hard to change once established (especially here on HN). This is why people with historical context do not trust Microsoft, with good reason.
That's weird, because my perception of the companies listed above is that they are exactly preoccupied with that.
The only reason I don't do it is that I'm afraid it won't be distinguishable from a small percentage of the HN readership who do so seriously.
Really, it gets boring.
Anyone who has been around long enough (and not really that long all things considered) knows better than to ever trust Microsoft. Their whole model has been, and always will be: "Embrace, extend, extinguish".
So Microsoft is opening some things up? They've had no choice as they are being left behind more and more. They know the modern developer is not as interested in an expensive IDE and MSDN account when there are many alternatives. We are creating so much more software than before and the top down model Microsoft sold has become niche after many years of dominance.
Any open project Microsoft gets involved in and any open standard they get involved in should come with a warning label. Why? Because this is in their DNA.