I honestly don't even get why people would want Steam to go to MS. I still consider them to be one of the biggest poisons in gaming, bringing about a lot of what I hate about it. Not that they're the only ones, but they have a proven history of pushing and creating:
-Moneyhats (Tales of Vesperia)
-Exclusive DLC (CoD for a generation)
-Paid online service
-DLC being cut content of a game added back in later to charge for it
-Horse Armor
-Xbox One's original vision and reveal and everything about it until the change
-Kinect
-Don Mattrick
-Games subscription service
-Games as a service focus
-Cancellation and mismanagement of games and resources (Rare, Scalebound, Lionhead, Phantom Brave Remake)
-Ads everywhere, baked into the OS
-RRoD fiasco
Again, MS didn't create all of this, but some of it, they most certainly did. If anybody has faith that they'd improve Valve in any sort of way, I'd question why they believe that.
It's really a shame, the original Xbox, I looked at much in the same way as a Sega console. Underdog with great exclusives and a fresh take on features. Even the 360 was a great console during the Blades days when they were still investing money on games and not just using the money to lock out competitors and do underhanded business practices.
I most certainly do not want MS to buy anything I actually like or use. EA I'd be fine with, because my opinion of them wouldn't change a bit no matter who's running the company. Whenever I see positives for MS owning Valve, it almost always relates to someone wanting that checkbox on their side for "console wars".