In a disclaimer or a Terms of Use document, there are often pages and pages of statements like "We are not liable if you do this", "We are not liable if you do this", "We will not give more than $50 if this happens", etc.
The sentence "You can't sue me" probably goes against a fundamental right that you can not forfeit, but why can't they simply put "By agreeing, you forfeit your right to make any claims against this company" or, more formal, "We are not liable for anything, related to the product you bought, or otherwise" in their disclaimer?