One "good enough" in stdlib means libraries could just require passing a interface matching it. Then no matter which logging package you use, as long as it fulfils the interface of stdlib logger it can be used with any library or other component you pulled.
So with simple app you can just have simple logger that dumps everything on stderr, complex app can have whatever complex logging logic it needs, but lib "just using stdlib logger" doesn't care about that.
And as a lib author, again, you can just use the stdlib one and most likely cover all your use cases.
One "good enough" in stdlib means libraries could just require passing a interface matching it. Then no matter which logging package you use, as long as it fulfils the interface of stdlib logger it can be used with any library or other component you pulled.
So with simple app you can just have simple logger that dumps everything on stderr, complex app can have whatever complex logging logic it needs, but lib "just using stdlib logger" doesn't care about that.
And as a lib author, again, you can just use the stdlib one and most likely cover all your use cases.