Interesting analysis. I said what I did half in jest, as you may now realize. The grain of truth within is that soccer is not a sport that (in its chosen incarnation) ever translated well to the U.S. professional sports mainstream. Failed leagues and flagging attendance figures testify to that reality: for as much as our educational establishments tried to push it upon students, eventually (as adults) their interests often returned to football, baseball, basketball, and hockey.
Last time I checked, MLS is plugging-along rather nicely. Turning a profit, (reasonably) filling its stadiums . . . .