Just because you are the best in your area does not mean you can't get better IMO.
I never said that. My implication was that it would be difficult to get
substantially better than your best player, assuming you're not anomalously skilled at the game.
Think about how Ken and Isai got so good back when the smash community was tiny.
They are/were both very talented individuals who innovated tactics which were effective on the population at large. But it's just like the fine print on weight loss commercials, results are not typical.
It is a limiting factor yes, and you would proable get better quicker if you had people who were better than you to play against, but it's not imposible. An example of trying to get better when your the best would be that you could thinking about problems in your play style that you have not though of befor and figuring out how to counter those problems.
The last paragraph of my previous post posited various ways of improving your playstyle, the most effective simply being playing more and different people.
Your style and ability are determined by what tactics you have encountered and how reliable you are at understanding and implementing new tactics as well as counter tactics. Very, very few people will have as meteoric a rise as Mango or Ken, not because many of us practice any less than they do, but simply because they practice the right things more than we do.
There is a set of tactics and heuristics people develop to deal with different playstyles when they encounter them. If you play a small group of people, your tactics become very specialized, you tailor your abilities to counter them. When you play a large or varied group of people your tactics become generalized, making them effective against a larger amount of people.
If you are one of the lucky ones and your specialized playstyle happens to be very effective on most people, then congratulations your playstyle and practice methods are likely very sound. Most people, however, are not so fortunate and will require a exposure to many different tactics/playstyles before they develop the ability to be successful on a large scale.