The problem, though, is that Link is scripted to win each and every time. Nintendo is copping out, eventually they'll start to retcon if that's the case. For example, SS--MC/FS--OoT. Where the hell did the Picori Blade come from and what is it, really?
Another situation is, if Link were defeated in OoT, then Ganondorf *would have* gained the Triforce of Courage, and knowing how he is, he'd go directly to Zelda and take her piece as well, becoming the 'true ruler of the world'. How then would he be sealed? The final battle still took place in Hyrule, not the Sacred Realm/Dark World. The sages alone couldn't seal him while he was running rampant, which is why they put LINK to the task of stopping him.