While I agree that it is annoying whenever one reads something put out by the actual SO people, I notice that (thus far) if I simply ignore that and go there to look up the answers to questions (and very occasionally ask or answer them), it still works fine. As long as the new owner doesn't make it "pay to see", I can probably ignore them.

There is, of course, no guarantee in this. But, while I find what I hear about Mozilla's internal politics obnoxious, I am also able to just use Firefox and ignore all that, thus far.

Plenty of examples of a purchase being the beginning of the end, but it's not inevitable. Microsoft owns Github. Google owns Youtube. So far, both are still functional, if compared to other real-world products rather than some theoretical ideal. Now, you could put hundreds of counterexamples on the other side of that, but at least it is possible for the buyer not to completely screw things up.