The reason is probably more to do with a little spat between Apple and M$ as their pact to have IE as the default browser came to an end.

FWIW, Safari isn't a completely new browser. It's actually an OSX development of Konqueror, the Linux browser. Apparently, a Windows version is also in the offing.

I can't imagine bothering with it too much in my case. All it means is that I will test less on my Mac.

FWIW, Safari has been my principal browser nearly since its release. To me, it's ability to automatically block pop-ups, something that IE refuses to do, is worth any small incompatibilities I've encountered (which have actually been few).