There's no benefit to Oracle in providing a general purpose server linux to compete with Debian, because there's no profit in it. They're providing this linux primarily so they can sell a vertically integrated stack with their applications on the top, and secondarily to get some revenue from the kind of companies that insist on big name support for anything they use. Debian does not compete in that market, and they're unlikely to have customers demand debian binaries because the kind of companies that run debian don't run oracle applications.