Debian in the form of Ubuntu is superb desktop, but it is exasperating as a server OS. It's based on the principle of constant updates which doesn't work in a business environment, where configuration management is king. Constant updating is particularly perilous with Open Source; I have seen point updates break things. Further, in a professional environment you want to stage updates. So for instance you might introduce Apache 2.2 in Test, but leave it on 2.0 for Staging and Production. Later you can introduce it in Staging and Production. This is just too difficult on Debian to bother even trying.

Enter Red Hat. RH understood the needs of business, and created a much more controllable Linux. It also introduced a new, extremely valuable, facility: the ability to stay on old versions of software without the associated risks. For instance, Apache 2.0 has a few known vulnerabilities and the only remedy from the Apache Software Foundation was to upgrade to the latest version of Apache. This left businesses in a quandary: Upgrade and risk almost certainly breaking the corporate web site, or just hope no one notices it's running a vulnerable web server. Red Hat had the solution: it back-ported the security fixes into Apache 2.0 and all was well. This is a service it provides for all its packages.

RHEL isn't a flawless business OSfor instance, patch auditing is a messbut it's what made Linux acceptable to the business community.