I've been using OS X exclusively for quite a few years now, and I'm not alone. Go to any web conference, and you'll see that we're all using Macs these days. Sure, our servers are running other stuff, and we may frequently use VMs, but OS X heavily influences the workflow for the vast majority of web designers and developers.
In a recent OS X upgrade (Lion), Apple decided "Save As…" was a menu option we no longer needed. I really tried to make myself believe that was an okay decision, but after several months, it was clear that it wasn't. I began relying more and more on doing filesystem stuff in Terminal, especially when it comes to managing copies of files. Over time, I noticed myself trusting the UI less and less.
I got all excited when "Save As…" returned in Mountain Lion. I upgraded immediately, even though I'm not usually the sort of person who would do that. I still had to manually add it as a menu option, but that's the case for all sorts of stuff. (There's even a GitHub project for sensible defaults.) I thought Apple had fixed their mistake.
Then, I read about people losing their data:
If one edits a document, then chooses "Save As…", BOTH the edited original document and the copy are saved, thus not only saving a new copy, but silently saving the original with the same changes, thus overwriting the original.
A quick test showed this to be true. Someone on Twitter suggested it wasn't a bug in "Save As…", but rather an aggressive autosave feature that made it seem so. I did a bit of testing to try to see which it was, and I discovered that it was aggressive autosaving. Before you even save a file under a different name, your original has already been changed, silently saved without letting you know. For your own good, I'm sure.
In video games, a standard workflow used to be that you'd save your progress when you were happy with it, restarting otherwise. I've watched friends fight a boss and quit immediately after each death. Since this isn't very cool, game companies started autosaving, so all of your progress, desired or not, would be saved.
For games, this makes sense, because only misbehavior is being punished. Why would you punish people using computers who do the same sort of thing? Is there some honor code among computer users that says you should never make a change unless you mean it?
This isn't a terrible idea in isolation, but it's clearly one that doesn't come naturally to anyone who's ever used a computer before, which is most current computer users. If someone more clueful were in charge of this effort, there would be a lot more education, hand holding, and genuine attempt to lead people to where you want them to go.
Apple often do a great job explaining new features. For example, when I first got my hands on an iPhone, I already knew how to use it. Everyone did. I wouldn't expect the same love given to such a small feature as this, but if Apple thought it was important enough to change how we're expected to interact with files, why is the workflow we're supposed to adopt not widely known? It should be nearly impossible to miss.
As it stands, a feature intended to help people prevent data loss is actually causing it.