I suppose the more charitable way to look at it is that groups like Red Hat (and now Microsoft) are the ones interesting in paying the people looking to do that work. Which is not to say it doesn't give them a lot of sway, but there's also only so many volunteer hours and you'll inevitably get more work done than others if you're getting paid to do it 40+ hours a week.

It's definitely part of it, the fact that they are major contributors makes their work much more visible. There's some amazing contributions from Redhat employees like Pipewire. They are one of the only companies investing into Linux as a desktop os and, personally, I do appreciate that.