Why would they do that? You can't do anything with an OS, and there isn't a single OS on the market today that wouldn't allow you to do basically everything that anyone would want to.
People get computers to run applications that allow them to accomplish something, be it wasting time on Facebook or designing nuclear reactors for power plants. What OS the computer runs is by far and large completely irrelevant as long as the needed/preferred applications are available for it.
Sure, if and when the problem reduces down to the point where basically all systems have the necessary software available for you to do what it is that you need to do, then the preferred OS will probably be the deciding factor.
And there are posts in this thread where people say that the only reason they are still on Macs was Aperture.
Let's just clear this up:
We're talking about pro/consumer/prosumer photographers here - Mass market. There's no analogy here with I.T infrastructure in institutions such as hospitals, or a "nuclear Power Plant"(!). I strongly doubt that a Nuclear Physicist is debating on whether to get himself/herself the next Macbook Pro or PC equivalent based on anything that has ever been said in MacRumors forums.
You contradict yourself a couple of times there, but essentially you're right - people do buy (or rent) computers to allow them to accomplish something - in this case making photographs. Historically, that has always made more sense on a Mac, and was somewhat diluted when digital photography became more prevalent and Adobe released Lightroom, giving PC users access to the same (or similar) DAM that Mac users were privy to.
Timings and Digital Asset Management are the key here. Aperture came after iLife, iTunes and so on. It was a natural progression from iLife back into the camp that Apple were at the time known for - Pro Apps. Remember though that Aperture was expensive on first release, and so slow to operate that it was almost unusable, and remained so at least until Aperture 2. By this time Lightroom was already under way, so Windows users also had a great option for DAM. Mac users had a choice. Lightroom was the better application for a long time (smoother to run, made sense with Photoshop, better updates etc) so if at that time anybody dumped their favoured Windows OS for the expense of buying a new Mac and then spending another £200+ on Aperture when they could have just gone with Lightroom (not to mention having to buy a new copy of Photoshop, Office, whatever else) then they'll probably admit themselves that they were in fact insane!
The same thing goes the other way: You're on a Mac, Apple kills Aperture, so what? You buy a windows machine? Dump all of your day-to-day stuff, relearn a by now new platform, buy new software at great expense, so you can use a PC version of Lightroom??! Why not buy or subscribe to er, Lightroom on the Mac?
And what happens when Lightroom becomes subscription only? If that's not for you, do you then dump your PC and see what Apple has to offer?
I'm calling it; People saying they are still on a Mac solely because of Aperture are bluffing. They're just lashing out at Apple because they feel that Apple doesn't want to listen, and in the smallest and most irrelevant way possible are hoping that by stamping their feet, sulking, and proposing such a minuscule exodus that they're sticking it to the man. They're scared of Lightroom, haven't looked at the alternatives and
Just Don't Want To Change.
It's just not fair.
Meanwhile, the rest of us have moved or are moving on.
