ehhhhhhh i'm not so sure about it.

I think the details matter. Curtain rods are typically 1-4" from the wall. This product looks like it works best <0.5" [0] from the wall otherwise it's possible the hanger will move around or have a "sagging" look.

Finding curtain rods that are that close is uncommon and limited in styles/options (I didn't see one on a quick amazon/aliexpress search). That's not to say you're wrong, but I don't think it's as simple as you believe it to be.

[0] https://ksr-ugc.imgix.net/assets/043/060/840/f8e1ace8b30ae8b...