The old documentation often wasn't good. But if you're trying to replace an existing system, it's a mistake to think "the old system had poor documentation so

The old documentation often wasn't good. But if you're trying to replace an existing system, it's a mistake to think "the old system had poor documentation so it's OK for the new system's documentation to be poor too", because people have already learned to cope with the old system. I've seen people make that mistake distressingly often in recent years.