Red Hat is like the 10,000 pound gorilla in the world of Enterprise Linux, and traditionally has walked a fine line (well, mind you) in bringing open source to the table against enterprise proprietary vendors.
Other open source competitors like SUSE and Canonical have much smaller revenues, so Red Hat could be seen as having a bit more influence over Linux's overall direction (they employ a ton of devs, they have a ton of resources). Case in point, the systemd controversy.
There's also a historic argument that one cannot trust FOSS in the hands of any corporation, but we start getting into more philosophical and nearly-religious debate at that point.
Not RHEL compatibility, because that's what Stream also has, the bug-for-bug similar behaviour is wanted when you have RHEL servers but test on Centos without having to bother with licenses or terms.
Other open source competitors like SUSE and Canonical have much smaller revenues, so Red Hat could be seen as having a bit more influence over Linux's overall direction (they employ a ton of devs, they have a ton of resources). Case in point, the systemd controversy.
There's also a historic argument that one cannot trust FOSS in the hands of any corporation, but we start getting into more philosophical and nearly-religious debate at that point.