Nothing like getting a call from a Director of IT who is in dire straights and needs help. Coming onsite we find whitebox servers in disarray, a hackneyed storage array running some version of Linux or ZFS, and everything being managed by a litany of custom scripts.
Why the troubles? The guy who built it all either left or did it wrong. His attempts to save the company money put them at risk and now they're having to pony up $200/hr for an expert or experts to come fix it.
Why buy server hardware from Dell, HP, Cisco, etc.? Why buy storage from Netapp, EMC, Tintri, HP, etc.? Because a large part of business is mitigating risk. Purchasing these tested, solid solutions reduces risk for the business and, more importantly, for the IT staff themselves. When a business is losing thousands or more dollars a minute during downtime, that $10,000 in savings by running everything on 1337 PC gear doesn't seem so significant anymore which is why big companies make the investment in enterprise grade hardware and software.
Do you really think all these industry experts, from industry CIOs, CFOs, research firms, etc. are so stupid for buying enterprise gear when little old you has it all figured out that your desktop Intel CPU and Gigabyte motherboard from Microcenter is really the way to go? Do you really think they haven't run the numbers, weighed the pros and cons, and analyzed the risks then decided to buy the needlessly more expensive gear anyway?
Know what happens to IT guys who build all this whitebox crap then need to call in the pros when shit goes south? They get replaced with people who want to actually act like professionals and not put the business and themselves at risk by saving a few thousand dollars with desktop gear to run their business critical applications.
This is the same reason I didn't pour the foundation for my house, do all the electrical work myself, tape, seal, and mud the drywall, etc. No matter what, I can't do it as well as the pros who do it day in and out for a living and know what they're doing. Would I have a house? Sure I would; a dilapidated, ugly, crumbling, piece of shit house that is entirely my responsibility to keep standing even as it falls around me and when it does eventually fall, it's my fault. This is why I pay, for example, $200k for a house that is actually $50k in building materials -- because the risk isn't worth it and my family needs a solid roof over their heads.
I will say, however, that whitebox or desktop gear makes sense for small mom and pop stores who can't even afford an annual $1,000 IT budget. I did it myself for a tiny company I did work for back in 2004. In that scenario, the risk must be taken on because the money isn't there to mitigate it.