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Not necessarily.

It's bad ethics to write something only you can maintain for self-interest.

If your boss tells you to throw hacks in or pile up a bunch of tech debt, it's your job to say, "this is ill advised, and here's why", and then do it anyway if that's his or her informed decision. There are often pressing business needs that mean having feature X now, and possibly paying more in the future to clean it up or for other features, is a fine tradeoff.

Lots of code is in the place, where test coverage is poor or there are grungy hacks to make things work, and hence is much more easily maintained by the original author.