Chrome permits access to ws://127.0.0.1 from https apps. I believe it's also making its way to Firefox, which is currently http only. Other browsers (ie/edge/safari) don't even follow this exception for http yet.
Could you give a link where this is discussed? I see crbug.com/378566 mentioned in another comment, but there doesn't seem to be a decision in there, apart from general acknowledgement that the use-case exists.