2) People barely take Bing seriously
3) Nobody cares about LinkedIn as a channel for free expression, nor is it a breeding ground for dangerous ideologies
4) Microsoft is generally much more enterprise-focused than these other companies, which all have very active footholds in the lives of regular people. When it comes to something like the power to make or break democracy, Microsoft really has very little impact by comparison.
It's not that Microsoft being so big is good, but it just doesn't have an impact on the masses that's comparable to the others.