You are thinking way too extreme. An API is still a hell of a lot better than a sketchy bookie. I would trust the former and not the latter. Which helps break up the centralization of betting because it is much easier to establish trust in a 3rd party source of truth than it is to establish trust in someone being financially responsible / honorable.

Will it improve the established market providers for sports betting? No. But that's the point. It enables people to make a small business betting shop