Yep, there is the issue, or at least the reason, why the US is no longer dominant in pool. There are just too many other players in other countries playing it now. Look at cars, electronics, anything really. The other countries watched, imitated, improved and equaled or passed what the US can do, just took a decade or two.
Not to start something that will get pulled into NPR, but it's not just pool that the US is no longer the leader in things in. I don't think the US has a lead in anything that at least one other country is known to be quality in. I mean when was the last time you ran into someone that went to the US to buy something they can't get as good in their own place? Last thing I can remember was Russians buying up Levis jeans in the 80s LOL. Hell, if you want to find classic US cars, you want to visit Cuba LOL
We don't have much of a cue sport export either, not that there are not great players, but there are great players everywhere now.