Comment by chikere232

> Makefiles are a good example. Every makefile author must write their own functionally identical "clean" target. Shouldn't there be an implicit default?

At some point you have to give the system something to go on, and the part where it starts deleting files seems like a good one where not to guess.

It's plenty implicit in other places. You can for example, without a Makefile even, just do `make foo` and it will do its best to figure out how to do that. If there's a foo.c you'll get a `foo` executable from that with the default settings.