Why do you think so? Microsoft has good developer tools of their own, Google is already building Android Studio on the IntelliJ platform without owning the company. Making IDE's is neither company's core business. I'm sure Jetbrains is a healthy business, but for Google or MS it's peanuts. I don't see the benefit of them owning Jetbrains, whereas on the contrary it would be good for Jetbrains to stay neutral.