Imagine inheriting a project that was a joy for someone to work on instead of a slog.

Joy is probably an improvement on slog, but one person's joy is another's hell. I've inherited a lot of joyful projects that were an awful fit for continued maintenance because joyful meant using new, unproven, and unstable technologies.

I have experienced many identical situations. Some people just love to tinker and over-engineer for the sake of stretching a muscle. It's unfortunate when that sneaks into a prod system that has to be maintained by others.

Parent developer's Joy is the inheriting developer's Despair. A project is successful when the parent developer is Bored.