I don't really understand the criteria, but...
St. Louis has about 300 members in the local Club. We have a nice schedule of non-sanctioned events (two or three a month) and three leagues with around 80 players each. Two other courses have weeklies that attract 12-20 players on a good night. We have seven 18-hole courses (five of them are good) and five 9-holes + a couple of schools that have some baskets on their property and a church camp that has an 18-hole course that they let us play if we follow the rules.
So we have a lot going on.
We also have a complicated thing with GDS in town, which makes plastic politics interesting. Actually we did a pretty good job of being on the outs with the PDGA before Dave started making discs. Not very many of our guys travel other than the GDS pros, and we avoided having an A tier for a long time. So, nobody ever says "disc golf mecca" and "St. Louis" in the same sentence. However I moved to Chicago for six years and tried to stay happy throwing short flat hyzer holes. I'll take the golf in St. Louis any day.