I agree with you. But the whole point of SPA or Mobile application is to provide a complete workflow.

You can of course implement autocomplete for payees, so once the user types "Joe" you show him list of suggestions by going to the backend. But what if your application is expected to have 200 payees max? Why not fetch all of them on app load? You avoid pointless calls to the backend by implementing typeahead functionality, you allow complete offline flow of transaction creation (if you don't have a payee list, you can not do offline support, because without the list you can't really create transactions) and etc.

I don't say REST is bad. But since I feel that it doesn't fit me, I suspect there might be a bunch of other people who feel like me, and maybe another solution was found. I've grown on REST, I know no other solutions, so I wonder what other solutions are there.