Yes exactly. Hence the quotes around the infinitely. Your chances of starting out with more entropy in a 800 char passphrase is likely to be larger than what y

Yes exactly. Hence the quotes around the infinitely. Your chances of starting out with more entropy in a 800 char passphrase is likely to be larger than what you are likely to have when starting with a 36 char passphrase. If you hash a 36 char passphrase then you retain most of the entropy of that 36 chars. No more no less. If you hash a 800 char passphrase then you maintain most of the entropy of that in the resulting 36 chars. Which is likely to be more.