It is not totally fine! React says not to do it! Fuck!

You just quoted react saying do it as a LAST RESORT not that it is fine. Pulled your head out of your ass and admit that you shouldn't tell people to use indexes as keys. It's sloppy, not what keys are for, and if you are working on a team, it's not going to get past someone like me. Quick Google search for literally jusy react index keys.

https://medium.com/@robinpokorny/index-as-a-key-is-an-anti-pattern-e0349aece318

https://medium.com/@vraa/why-using-an-index-as-key-in-react-is-probably-a-bad-idea-7543de68b17c

https://menubar.io/react-keys-index

And for the grand finally, looks like react even provides examples now where reorder issues can occur,

https://reactjs.org/docs/reconciliation.html#keys

Do not tell people it's OK to use indexes. Swallow your damn pride.