It's certainly true that IBJJF competitors are typically much higher level than regional competitors. I can win or medal in regional competitions regularly, I have never medalled in the IBJJF or even really come close. That said, the people who win local tournaments are most likely good for their belt level. They're just not professionals, which is essentially who wins all the big IBJJF tournaments at every belt level. That would be a pretty high bar for being good. In general I think anyone who competes regularly is already going to be better than the vast sea of non-competitors at each belt level.
The way I see it, you have 3 broad levels of practitioners: non-competitor hobbyists who vary greatly in quality but usually aren't that good for their belt level, amateur competitors who are typically the best people in their (often small) gym at their belt level, and elite competitors who typically come from big gyms (sometimes they move to train at those gyms), regularly train more than once a day multiple times a week, and who focus their lives on succeeding in BJJ competition. I actually think these people should probably be in a different division from true amateurs, and should also be compensating for winning. They are pros in every sense other than getting paid.
Regarding the OP, what you find is that since quality varies so much more at blue than purple that while in blue belt divisions you might have some easy and some tough matches, in purple belt divisions almost everyone will be quite good and very dangerous. I think I only had maybe 1-2 easy matches at purple. I've never had an easy match at brown, though I haven't had many yet.
