It's not always that. Sometimes (especially in smaller companies) the technical staff just leaves. Sometimes they get better offers. Sometimes they go off to st

It's not always that. Sometimes (especially in smaller companies) the technical staff just leaves. Sometimes they get better offers. Sometimes they go off to start their own company. I know some of what the OP is describing. I'm dealing with a system that's got three layers, each written in a different programming language. It was written by a pair of very brilliant programmers, who were unfortunately rather bad at documenting. They left the company when an after-hours project they were working on turned into a viable business opportunity. When I deal with this system, I can piece together the what, but the why often escapes me, only to bite me later when I try something and it fails horribly. Luckily, I'm only dealing with software. I suspect that it'd be much more costly to deal with failures in OP's case.