The podcast app I use has this as an option, it's not mandatory. Personally, I wouldn't use it if I had to sign in, syncing is not a feature I care about one bit and I don't need even an ounce of friction between me and "Wait Wait Don't Tell Me." If I had to sign in to listen I'd just turn on the radio or something instead.

If its truly about improving consumer experience its optional. I am not required to login to Chrome or Firefox to use them even though some people find bookmark/history syncing to be useful features.