Um, most if not all kids who attend Deaf Schools aren't in this Deaf only bubble........And trust me, it's a lot harder to develop networking oppertunties through a mainstream school for low incidence kids. ....there's a LOT of prejudice out there, and it is near on impossible to find disability friendly employers. Instead a typical experience is that a dhh kid applies for a job, and then a dumbassed middle manager takes one look at your hearing aids or hears your voice, and suddenly there's not a job available....
Besides, if your theory was correct, there wouldn't be a huge unemployment rate among people with disabilities....Most kids are indeed mainstreamed/suffer through inclusion. Hasn't made a dent.