That's a good reason to have shared responsibility of code. There is no one owner of a codebase, an entire team should own the code. An entire team leaving at once seems highly unlikely.
But if someone goes "lone wolf" and writes an application in a language he or she chose without informing other members of the team/organisation something else might be going wrong in the chain.
I get the idea you're trying to convey here but in the case of a well-organised team/organisation that won't really fly as everyone will be involved at some point and choices are being made together.