https://github.com/microsoft/TypeScript-Website/issues/2804
Contrary to many people's perception, Microsoft is one of the biggest contributors to open source, whether for projects they "own" like TypeScript or VSCode, or other common projects like Linux. The amount of users and bugs/feature requests etc don't match headcounts available at Microsoft.
So this isn't some sneaky Microsoft thumb on the scale, the way you appear to be implying. Simpler than that: I doubt many projects know about this list (I for one just saw it for the first time), and since GitHub put it together, Microsoft codebases got the memo to add the tag.
If you want to see other popular projects at the top of this list, open up a PR to have them add the tag.
I feel sorry for all the naive developers who will waste their time working for free for a parasitic corporation.