A company where I used to work still had those as of early 2020. The reason was technical debt, system being treated as a "black box" since the people who built

A company where I used to work still had those as of early 2020. The reason was technical debt, system being treated as a "black box" since the people who built it left many years ago, etc. In addition, that product didn't exactly make big bucks for the company so there was not much incentive to improve things.