If you are an official trainer registered and earn badges towards the Pokemon League, I assume you are awarded money if you win. Pokemon Center usage is free, etc...
I guess it had to do with Gold & Silver Games, despite giving us things like breeding, a full color palette, and the night/day mechanic, it was mostly the same game as Red/Blue/Yellow so the showrunnera probably thought they should do the same thing in regards to the Anime..
Ok, just happened to come across a video with a smidgen of Pokemon Commercials from the 90's. I remember some of them, but yeah Pokemon Anime, and by extension the franchise as a whole, was immensely popular back then...