I happened to be in a tab created by a command-click of a URL in the previous tab; there was no "back" in this case - so it did _exactly_ the right thing - it closed the tab and returned me to the previous tab.
This is precisely the thoughtful design that Apple is known for:
- Some of us (developers) know it directly, and know how much work it takes.
- And the rest of us who use a Mac, iPhone, iPad, etc., know it simply because, when the interface surprises us, it's usually a pleasant surprise.
A delight if you will - which is actually an explicit part of the official Apple Human Interface Guidelines.
That's a lot of hard work, which is usually (by design!) unnoticed - the point is not the device, but what _you_ want to do with it.
Although, every once in awhile, it's nice to appreciate - thanks, folks!