Almost all of the software products in adult are written by people with amateur-level skill-sets. Some of the most famous ones aren't even object-oriented.
The trivial skill-sets required to extend these applications can absolutely be outsourced.
Building from scratch, however, is not recommended with outsourcing. You're better off paying a competent programmer to lay the groundwork, and then direct the outsourcers as the project grows .. or you'll pay a LOT more in the long run than you save in the short run.
Hope that helps!