If you don't want them, don't use them. Make doesn't need you to produce actual files called 'clean', 'build', etc. you don't even have to do anything special unless your build folder has actual files called those things (in which case, you could declare them as phonies).
From Make's point of view, they're just target names. Make doesn't care whether or not a target produces any files. Targets can satisfy dependencies for other targets, as can files on the filesystem.
There are so many things where that’s not relevant. “Just start” or “just test” or “just install” are idempotent, or at least stateless (assuming “start” calls out to systemctl or such).
That's all true, but understates the important of a nicer UX. I've spent lots of time over the years working around Makefiles' idiosyncrasies. It's so good at its intended purpose that it's tempting to use it for vaguely related tasks. Turns out it's not as good for doing those things it was never designed for.
"Just" reimagines what make could look like if it were designed to be a task runner instead. That hits a sweet spot for many of us. It looks like the Makefiles we're used to, minus the pains in the neck we've tolerated from abusing make for our own purposes.
From Make's point of view, they're just target names. Make doesn't care whether or not a target produces any files. Targets can satisfy dependencies for other targets, as can files on the filesystem.