Isn't this being held responsible for it?

Yes, this "section 230" treatment of online platforms is at the core of why social media and the internet in general is full of garbage.

If you sell something on your site, or allow users to post something on your site, you should have some liability for the consequences.

they are responsible for it, but it's useful in reporting to differentiate between "fulfilled by" and "bought through"

> If the product is sold in your site, you must be responsible of it.

But this is an internet store.