I should note the idea of the "taproot assumption" which illustrates why Schnorr really helps taproot specifically: schnorr allows a multisig which looks exactly like a single sig. This means that N parties can use the scripts part as above to have complex contracts between each other, but the taproot assumption is that it'll always be valuable to have one special contract clause: "everyone agrees", and that is handled by a multisig on the pubkey *which to the outside world looks exactly like single sig signing*, retaining maximum privacy.