I think normally these kind of announcements would come from Yamaha - but I "stumbled" upon the sale when looking to see if I could find something on Yamaha Musicsoft. FYI - this is an official site Yamaha runs where you can get expansion libraries for Montage and other Yamaha keyboards. From time to time, there are site-wide sales. It's a good time to try out premium content at a discount. Montage has a growing collection of dedicated content and also much of the MoxF or Motif XF content is compatible unless you run into the problem translating certain encodings (see "inspiration in a flash" problem).
Purchasing content also promotes creation of more libraries as, after all, the content providers are running a business as well as providing quality libraries. Your purchase, in aggregate, helps keep the lights on and pay for sound engineers / recording time / instruments to sample / etc.
I don't get anything out of this - I'm just a keyboardist like many of you. I've missed these sales before and would have appreciated someone making me aware. Have a happy holiday / new year all.