This is not a "Houston" thing.. This is an "America" thing. And I am gonna have to make a note on your "bunch" of players 650-750 claim, re: Houston. There is a huge gulf in between 650 and 750, and America as a whole has less than 45 players above Fargorate 750, and many of them are no longer really active. 650-700 isn't anything really special, to call a spade a spade. I am part of a fairly small club here in Germany, and we have three 650+ players. In the region/ Prolly around 20-30. And it is not an especially populated area I live in. Mostly farmland.
Cost of Living in America has gotten so outrageous, that there's just not a lot of money floating around to support a niche game like pool. There are very few options for a young talented player to economically participate in the game, without either being affluent enough to own a table, or living close to a pool hall, and being first allowed in.. And second, being able to afford the table time. Pool in America is COMPLETELY built off of access to pool halls. Pool in Europe is built almost EXCLUSIVELY on private clubs with all the pool you could possibly pay for about 40 Euros a month. And that includes league membership/fees. And a key to the club, so you can play 24 hours a day.
And America, for better or worse, has tied the development of young players.. To gambling. If there's no money for the "regular Joes" in the economy to piss off a few hundred without it super negatively affecting their finances, then less people are gonna gamble. The best times for pool in America were during WWII, where a bunch of G.I. had a lot of money to burn, shipping out through Norfolk, and willing to gamble that money, as they didn't know if they were gonna survive to spend it. Almost all the great gamblers you have heard of in pool came out of that era of easy money.
In Germany.. Pool isn't like that. Pool Clubs operate in a "Bundesliga" system, and welcome young players with open arms. Clubs compete to move up in the Liga system, and as such, all the members of a specific club work collectively to help each other improve. There is a national youth training program, funded by a portion of the yearly league dues each member of a club pays. This youth program identifies players such as Filler when they are still preteens, and then the Germans do what the Germans do, and apply systems, fundamentals, to get these young players off to a good start.
Now.. Think about how players such as Billy Thorpe and Skylar Woodward got started. They showed some talent.. Hit 750+ Fargorate level... Gambled and soaked up all the easy money they could.. And then, and ONLY then, once they got through all the easy money.. Did they begin to take the game REALLY seriously, and try to compete with the big boys. By that point.. All the little idiosyncrasies in their stroke/game were baked in. These same flaws hold them back still on the world stage.
Filler was competing in Eurotour events when he was like 11 or 12. He's had world-renowned coaches helping him with his stroke/game from before he was 10 years old. This is what happens when you are raised in a country where gambling is simply not a priority.