It seems like more or less everyone uses Steam at this point, yes? It’s fairly ubiquitous? The service managed to hit a concurrency record on January 8th, with over 14 million people logged in and using the service at the same time. The most popular games being played at the time were Dota 2, Grand Theft Auto V, and Counter-strike: Global Offensive, all of which are online titles to some degree.
How you’d like to read these stats, of course, is up to you. You could, in theory, claim that this is a sign that Steam’s online functionality is increasingly vital to the game industry; you could also claim that any stats on a title from Steam only come from a fairly small sample size. You could also just be happy about big numbers. Whatever floats your boat.