You are talking about money when their point is that it was a huge success as a product and it influenced a sea change in development practices. I would only ask if their revenue was enough to keep the lights on, if it id then people are getting employed and the community gets a valuable service. Wicked.
Current revenue is not the right to focus on for an early stage acquisition.
They collectively raised $13M through the Series B in May 2010 and were acquired for $212M cash in December 2010 (technically ~$250M for the whole deal).
A ~16–19x return, especially that early, is pretty excellent.
That speaks to the product itself and its future growth potential and place in the market more than current revenue.
And then, Salesforce didn't really know what to do with it, and growth slowed down and good leadership left.