You can dismiss anything you want to, you're completely free to do that. Whether it's wise to dismiss a particular thing is a different matter. And there are many assertions that are wise (or just true) but that come with no evidence, for one reason or another.

This maxim is just another excuse for so-called skeptics to deny and dismiss out of hand anything that hints at there being magic or mystery in the world or anything paranormal, extraordinary or in some way paradigm-changing.