[JadeNB]

> The patterns and rhythm only exist when spoken.

Pattern can definitely exist in writing without being spoken. (Sometimes only in writing, and not when spoken; see, for example, https://en.wikipedia.org/wiki/Concrete_poetry.) I would argue that rhythm can as well, though that's less of a slam dunk.

[pests]

I feel certain poets like e e cummings require an aspect of being written as well.