Anything short of that isn't best; it's a compromise. Once information security starts thinking in terms of compromise, it's in danger of recognizing there is no such thing as a best practice, only practices that fit particular situations best. "Best practice" means one size fits no one. Nonetheless, those who declare such things insist that only fully locked-down personal computers will do.
So if Jane in property management figures out that taking pictures of properties on her digital camera and using, say, Microsoft ICE to stitch together 360-degree views would be useful, that's just too bad. Enable the SD card interface? Let her install a free downloadable program from the Internet? The risks dwarf any possible business benefit.
Instead, Jane goes home, plugs her camera's SD card into her (more powerful and up-to-date) home PC, installs ICE, and emails the result to work without her house ever once exploding. This is the same reason why, years ago, I chartered the Value Prevention Society (VPS) to provide a home for those bent on, well, preventing value by locking down user devices.
Challenge No. 3: The tale of two everythings
Jim travels. In addition to a career, he has something many of us call "a life." He's in the habit of checking his personal email, Facebook, and LinkedIn from his hotel room. He also calls home from his hotel room to talk with his wife and kids. Sadly, his company has implemented a common thought process about personal technology: The company owns it, so it should be used for company business only. As a result, he carries two laptops and phones with him when he travels.
Challenge No. 4: Stockholm syndrome
As is well known, after a while, hostages often start to sympathize with their captors. In similar fashion, after so many years of overseeing tight personal technology budgets, locked-down desktops, and all the other VPS policies, many CIOs consider this sort of behavior not just normal, but reasonable. It isn't -- there's a difference between giving up because something is politically impossible and rearranging your neurons until they accept it as actual sense.
BYOD, BYOT, and now BYOC prove they aren't. Each has been a response to the above-listed challenges. Instead, BYOD and BYOT should have been a response to opportunity, one that likely would have rendered BYOC unnecessary.
The opportunity: Increasingly computer-literate employees
Many employees own laptop computers. These systems are portable, more powerful, and more up-to-date than the computers they use at the office. They have plenty of unused storage. If their owners were allowed to work with them at the office, they'd also make office life more pleasant and productive.
Most of these same employees own smartphones as well, along with tablets. They'd be happier using these at the office, instead of having two of them or doing without during the work day.