Between your own accounts is the main use-case because you typically can't transfer between different banks.

> you typically can't transfer between different banks

WTF? What kind of shitty banking system are you using?

Wells Fargo said to do it I had to use Zelle.

Wow. You guys really need better banking regulation.

AFAIK Zelle is something US banks got together and set up on their own because the government didn't. So a Zelle transfer is the US equivalent of a SEPA transfer.