The argument to make to the backend team is a bit nuanced but it’s this: Generally each PUT/POST sent to the backend should have atomic semantics. If there’s some user action (like uploading a CSV) that should entirely succeed or entirely fail, you want to send it in a single HTTP request. If it matters that it happens exactly once (like submitting a forum post), then adding a nonce of some sort is a good idea too - just in case the request succeeds but the response gets dropped and the user retries the action.

It’s often tempting to model URLs like database entries and send multiple requests to the server to model updating many records based on one action. That’s a mistake - have the client name the action, send one http request, and execute it in a single database transaction in the backend if you need to. This approach is way more reliable, debuggable and consistent. This sort of thing is absolutely the backend’s responsibility.