I am sorry that happened to you but it sounds like it was for the best. I work at a place where knowledge sharing is pushed for. Everyone shares what they know. It makes things so much easier even if we do "waste" time cross training.

My last job was me replacing the inhouse developer, I got it by demonstrating on the interview that I could reverse engineer his code. The versions he had put into production had all the comments stripped out and he had replaced every variable with random alphanumeric sequences about 8 characters long.

Shouldn't have known right there and then what kinda workplace I was dealing with.