I think the tendency for devs not to document what they're doing betrays a lack of empathy for their colleagues. When you write a system, you are now the world

I think the tendency for devs not to document what they're doing betrays a lack of empathy for their colleagues. When you write a system, you are now the world expert in that system. Why not write a few words to explain the system? Save an hour or two, each, for everyone who needs to maintain your work? Why not link to the docs of the dependency you choose to use, or the forum posts or white papers that helped form the idea?