Criterion "Multiple Implementations" : use W3C "Three Is" instead?

Of all the criteria, the one I actually feel the most strongly about is multiple implementations, which I feel is very loosely specified compared to, say, the W3C TAG review process, which often rejects otherwise-final specifications for lack of a second (independent-enough) implementation! W3C's current language, central to the Technical Advisory Group (TAG) review process, is that specs need to document "**interoperable, independent implementations**" (the "Three I"s), and I personally feel we should adopt _at least_ this standard of "independent".

If you're not familiar with W3C, [this thread from the public Advisory Board repo of W3C](https://github.com/w3c/AB-public/issues/141) is a good place to start (bonus: it also contextualizes the "abstract data model", i.e. why W3C didn't just ask DID WG and VC WG to just pick JSON-LD _or_ plain JSON, and instead went along with the Abstract Data Model format). As part of TAG process refinements, [more operational definitions of the 3 Is](https://www.w3.org/wiki/AB/2024_Priorities#Interoperability_and_the_Role_of_Independent_Implementations) were researched, and the values of _INDEPENDENT_ implementations in particular were laid out in [this wiki](https://www.w3.org/wiki/Independent#Why_independent).

Currently, we are only requiring:

> Multiple Impls: Multiple implementations (include proof of multiple implementations, could be in the proposal file at column 4)

I would like to get more concrete, something like

> Multiple feature-complete, tested, stable end-to-end implementations with no code or libraries in common (ideally open-source)

I feel like a quick glance at `package.json` files (or their equivalent manifests in other languages) and a few clicks on github/package-managers is usually enough to unearth shared dependencies, so I don't think this increases the workload for review.

Thumb up if you're generally in favor of this kind of additional scrutiny, thumbs down for status quo, confused-emoji if you are on the fence/undecided/confused. Also happy to debate minutae or field better wordings here in the issue thread.