In two of your cases this operator is pretty shit because at some point you'll probably want to offset the access (this isn't a knock at you but at the feature).

This operator would only really be relevant to the last case which rarely comes up outside of infrastructure/library work (building a tool building tool) and usually those code bases are cautious to adopt new features too quickly anyways for portability.

I've done serious C++ work (not much in the past decade though) - while references are absolutely amazing and you essentially want to pass by const ref by default I think well written maintainable C++ should maybe have a dozen heap objects tops. C++ is a better language if you generally forget that pointers and bare arrays exist.

Just again - I think you're right and the fact that your list is only three things long (and arguably two of them would be misuses) is a pretty clear sign that this is an incredibly niche feature.