In this particular case it's all about Windows not having a decent SSH client. There's PuTTY... and uh... PuTTY. Oh, and you can sort of maybe run OpenSSH through LSFW or Cygwin, or maybe msys, but those all have some serious gotchas associated with them. Basically it boils down to, there's no standard Windows SSH client, and the ones that are available all have a laundry list of gotchas and problems, and that's without even bringing in the various git clients into consideration. OS X and Linux are low hanging fruit, they both come out of the box with a standard and well supported SSH clients.