One thing you hear from seasoned meditaters is that meditation is useless. Generally they mean that meditation can help you learn more about yourself and your thought process, but there is no guarentee that it will achieve any results. I may not make you calmer. It probably won’t improve your memory. It may not even make you perform better at work. It not a thing you do to make yourself better.
I always thought this concept would make for a good Abbot and Costello routine. I might even be able to make a mini-comic out of this.

So they say “meditation is useless” but they really mean “meditation *might* be useless”? They should be more clear about that.
Yeah, Zen has a notorious history of not being clear about things.