I always assumed there was an "Oracle Applications 10" package before 11 (with or without the 'i'), before I joined the company.

In fact, I seem to recall seeing an old manual for 'em lying around somewhere at the office... (No guarantees, though, my memory could be wrong.)

So what happened to 10 was, AFAICT, what happens to pretty much all computer applications: It was superseded by the next version. (And if my memory above is wrong, then... So what? Then they jumped one or more numbers in the versioning; wouldn't be the first time somebody does that.)