Earlier quoted context omitted.
Hasn't Office always been available for the Mac?
In a limited way. Word, Excel, Outlook, Powerpoint, and Communicator (i/o Lync) are available for Mac, but they are not even close to the Windows versions in terms of feature parity. VBA support has been on-and-off. Access, Infopath, and Publisher are not available at all. They're written in Cocoa and on a different release cycle. There is no Office for Mac 2013, current version is 2011.
Excel had a pretty nasty regression on the Macintosh in Office 2004/2008 (to the point at which I no longer used it on the Mac in 2008, it was pretty horrid) - but they returned it to (mostly) feature parity as of Office 2011.
Sharepoint, on the other hand, is complete crap on a Macintosh. It's almost like it's been designed to be bad.