The problem I have with following any team video game is that there can be many points of focus.
In pretty much every televised sport, the ball is the point of focus. If the ball goes to one person, the people on the other side of the field don't really matter. In CS:Go or a MOBA, you can have a lot of stuff going on simultaneously that is not easy to follow.
That goes double if you are trying to display it TV-style where it can be followed from a distance. It is one thing to watch a HOTS match fullscreen sitting in front of your computer: you can see the minimap, you can see the respawn timers, the objective timers, etc., and maybe you can look at talent pics and ability cooldowns. Compare that to when ESPN2 televised it. Losing the minimap and that meta information and having to rely on only what the "cameramen" showed you made it hard to follow as someone who has actually played the game a little bit. I imagine it was next to impossible to follow for someone with no familiarity.
If you took an american sports fan, sat them down in front of Australian rules football, and told them to root for the red team...they would be able to follow the action. Some rules wouldn't make sense, but they would know when their team made a good play or when they were getting hammered. Same would be true if you showed them many other rarely televised sport that they weren't already familiar with (lacrosse, field hockey, ultimate frisbee, etc). Hard to watch Dota, LOL, or HOTS without being an avid fan who is familiar with not only gameplay, but also the abilities and interactions of 30 different characters.