> If you decline the new contract, you're entirely welcome to continue on the old T&C.

I think the point of contention here is that in practice, there is no way to continue on the old terms of service/contract. Suppose you're using a note taking app, and one day they update their terms of service to say that they can use your notes to train their AI. "Continued use implies consent," so you are locked into the new terms of service unless you stop using the app right then and there. You are not afforded the opportunity to decline the new terms of service and continue on the old ones.