Despite "COD for online" myth, most people do, according to achievements. Less than 50% of the players have rank 10 in BLOPS 3, which only takes about 2 hours to get with quite mediocre skill, so basically they didn't even bother with online:
http://steamcommunity.com/stats/311210/achievements
Online is not nearly as popular overall as it would seem from internet talk. Usually only about 15% play competitive multiplayer modes with some consistency, and less than 10% really get into it. MK X is typical case, 37% beated story and 35% won single online match:
http://steamcommunity.com/stats/307780/achievements
In grey goo, 5% won a single 1on1 match, but from the talk on teamliquid you could have thought that was supposed to be bread and butter of RTS games:
http://steamcommunity.com/stats/290790/achievements
I also have strong suspicion that for MOBA games most games are played vs bots too, can't prove it though.