Why there isn't (and shouldn't be) a Grievous Wounds AD item

I've noticed a few threads asking for a AD item with grievous wounds. I would like to address why this is a terrible idea.

AD champions already counter sustain based champs. Sustain based champs are very weak to sustained damage. AD by its very nature is more sustained than AP because it also scales auto attacks. Sustained based champs are good are short trades that they'll most likely lose, then sustaining back up. These champs are extremely weak to heavy all ins and champs that can repeatedly force trades with them.

Lets look at for example. Vlad is extremely weak to the vast majority of AD top laners. all pretty heavily counter Vlad. Why is this? Because they can continue to force trades with him before he can sustain back up. These champs can continue to follow Vlad after his pool and force all-ins that Vlad will lose. Vlad can't really ever duel any of these champs unless they make a lot of mistakes.

This same logic also applies to early game. Mundo gets wrecks by most AD champs just because his early sustain can't keep up with the constant damage

So why do we need an AD grevious wounds item? It would only put the nail in the coffin for pretty much all sustain based champs. AD already counters sustain-based champs without grievous wounds. If we introduced an AD Grievous Wounds item it would be complete overkill and completely uneccessary.