In what use cases is this superior to traditional metal-glass seals (e.g. vacuum tubes), or metal-on-glass deposition (e.g. mirrors)?
This is a constructed example to demonstrate the type of thing that could be done now that we've figured out a possible way to do it. It's probably not a good example, but it is clearly distinct from the thin-film processes we consider common today.
EDIT: See below’s multi-paragraph writeup of why my “now you can do this” example is not a good example in practice.