Beyond what has already been mentioned above, why sell something that was losing money?  There's an ex-employee posting over at Reddit (see link elsewhere in this forum) talking about exactly what happened.  In those posts he reveals that Cakewalk themselves were not making money.  If correct, then Gibson would have had some issues trying to sell them.  "WE" like to think it's a great product and an awesome buy for someone but, let's admit it, we're a bit biased here and not approaching the topic from a purely business decision point of view. 

pharohoknaughty
The late 80's and early 90's were critical for market share. Protools was getting the rep as a pro level tool, and the others were for weekend warriors. (I didn't agree with this reputation but it was that was going on).
 
Cakewalk was really only marketed in the United States. I remember Europeans on the forum asking to buy, but were pushed away. Eventually Roland became the agent for sales outside the US, and Roland treated the software very passively. It remained difficult to buy it in Europe.
 

In the early 90's I lived in the UK and back then, unless you were using a tracker program like ProTracker or OctaMED (which I was), or doing everything on hardware, the main two options were Cubase and Cakewalk. It seemed to me that there were far more Cubase users, but nonetheless I distinctly remember Cakewalk being on display alongside Cubase in my local music store. So they must have gotten into Europe to some degree, even if it was only Britain.