The writer missed the real reason that football (soccer) is not popular in the US....TV.
Soccer does not convieniently stop for commercial breaks the way that the other US sports do. This makes it VERY unpopular with the networks and advertisers alike. So you won't see it on TV with the same regularity as the other big 3 US sports.
The sport also doesn't stand a chance at developing into a fan favourite. Just look at College football in the US. It earns more revenue for the Big League schools than anything else. Soccer hasn't even got the POTENTIAL to earn the same dollars as football or even basketball...so US schools will not promote it in the same way.
It is sad that such a great game is dismissed by Americans....all because of the mighty TV.