But often tasks are a step removed from that. Targets like "all" and "clean" are good examples of useful tasks to have, even if they're unrelated to files.
A "task runner" isn't intended to replace all of a Makefile's functionality. It takes a common use case of Makefiles, and improves the user experience for this.
I think it's fair to say that it's not a big step up; but it's a definite improvement for what it does aim to do.