For Red Hat, there's no longer an official "public" distribution of RHEL, but apart from that they seemingly have been left alone and able to continue to develop their own products. But that's only my POV as a user of OSS Red Hat products at home and of RHEL and OpenShift at work.
The culture makes the company. Everyone on the lower rungs of the org chart knows this, because it's what they live and breathe every day. A positive, supportive workplace culture with clear goals and relative autonomy is a thing of beauty. You routinely find people doing more work than they really have to because they believe in the mission, or their peers, or the work is just fun. People join the company (and stay) because they WANT to not because they have to.
Past a certain company size, upper management NEVER sees this. They are always looking outward: strategy, customers, marketing, competition. Never in. They've been trained to give great motivational speeches that instill a sense of company pride and motivation for about 30 seconds. After that, employee morale is HR's job.
I have worked in a company that got acquired while it was profitable. The culture change was slow but dramatic. We went from a fun, dynamic culture with lots of teamwork and supportive management, to one step or two above Office Space. As far as the acquiring company was concerned, everything we were doing didn't matter, even if it worked. We had to conform to their systems and processes, or find new jobs. Most of us eventually did the latter.
Somehow Red Hat seems to be a notable exception. Although IBM owns Red Hat, they seem to have mostly left it alone instead of absorbing it. The name "IBM" doesn't even appear on redhat.com. Because I'm an outsider, I can't say whether IBM meddled in Red Hat's HR or management, but I would guess not.
1. https://www.cio.com/article/4084855/ibm-to-cut-thousands-of-...
2. https://www.newsobserver.com/news/business/article312796900....