You got a very good point here. Look like the big names, it's good for image. Especially when you have a terrible image like oracle starts to have. ( or did it have it since a few years already? )

It goes further than that: There's a certain set of people and corporations that started out with Red Hat Linux, and prefer to stay in that ecosystem (known tools, available work force).

By claiming you're RHEL compatible, you "merely" compete against Red Hat, Cent OS and some other clones that some might not even have heard of (eg. Scientific Linux).

You automatically exclude Ubuntu, Debian, Suse and so on, but while reasserting that RHEL compat is somehow important, you push them to the defenses, not yourself (except from the point of view of Ubuntu, Debian, Suse, ... fans, but you won't convince them anyway, so why bother?).

That might be a reason why Red Hat doesn't bother too much about the clones: they make the RHEL ecosystem stronger, provides incentives for RHEL certifications, and RH can still try to upsell Oracle Linux users for the "original".