I get very little value from proofs in math textbooks, and consider them usually unnecessary (unless they teach a new proof method).
I think the problem is that proofs are typically optimized for “give most convincing possible evidence that the claim is really true to a skeptical reader who wants to check every possible weak point”. This is not what most readers (especially new readers) want on a first pass, which is “give maximum possible into why this claim is true for to a reader who is happy to trust the author if the details don’t give extra intuition.” At a glance, infinite Napkin seems to be optimizing much more for the latter.
I think the problem is that proofs are typically optimized for “give most convincing possible evidence that the claim is really true to a skeptical reader who wants to check every possible weak point”. This is not what most readers (especially new readers) want on a first pass, which is “give maximum possible into why this claim is true for to a reader who is happy to trust the author if the details don’t give extra intuition.” At a glance, infinite Napkin seems to be optimizing much more for the latter.