Wham. Some of us have slammed into gear-centric thought. And, incidentally, fascism. The old "the masters have shown us the way and that is the only way" school of thought.
The "only valid application for multi-exposure"? Please. If the camera can do it, then to take advantage of a camera's capability is inherently a valid application of the medium. Generalizations like "esoteric" and "amateurish" are just that - generalizations. Which, by definition, do not apply to individual images. Every image, every approach, must be informed by and evaluated on its own merit. This requires effort and disciplined thought. AND DEFINITELY NOT PRECONCEPTION.
Tarot cards are not depictions of anything but archetypes. So then, are photographs to depict anything but non-archetypes simply because they are not Tarot cards and are capable of very accurate renditions of a moment in time? Rhetorical question. Then, if photographers have the latitude (incumbent and inherent in the medium) to depict anything they wish, including archetypes, then why not a thousand exposures? Where is it written that you may only depict things - concepts, abstractions - by a certain restricted method?
Juan. You can do what you like. Don't make it a requirement for others. There is no possible consensus for metrics as measurement of rendition as a constant in a work.