I think "won" means that when you are making an argument to introduce a piece of software into your workplace there is a technology that is more widely used. It doesn't necessarily mean that one is better, but there is usually a reason a technology is widely adopted. If you don't fully understand the advantages and disadvantages of similar products then widespread adoption can help with the decision.
Also it's not true that a lot of forward-thinking, progressive, thought leader tech companies are using Lotus Notes. That is true of mercurial.