Earlier quoted context omitted.
I think this is a good explanation, however don't you find that you have to be a player of the game in order to enjoy watching it? Not being a MOBA player, I can never understand what is going on when watching games like DotA.
Just like regular sports, you need to understand the basic rules, but that doesn't mean you need to know all of them. Most people don't know the full rulebook of sports that they watch. And commentators can make it even more accessible; their expertise is there to help provide context and guidance.
In football You don’t need to know, exactly, which way the plays are going to go and why, but you do need to know the rough constraints of the game and what is physically possible to perform.
Some of the things that happen in dota are utterly impossible to follow unless you have, at the very least, a knowledge of the (on average 3) active abilities of the ~110 heroes.