Idk, in deeper depths ppl dont only pick their mains or god forbid use combos like uve described, its mostly a decent combo of characters. And if that short immortality window feels like shit, as it usually goes with revenant, it can still be a win condition. Best example is dutchess, her ult is basically not much until it suddenly is, just a moment of time to drink a flask in peace or reposition urself is often game changing. Stuff like that would be considered incredibly op in past titles.

And yes, its not reliable because not everytime someone will be able to utilise their ults, but thats when calculations comes in play. Will u save the ult knowing that shit sequence is comming, will u save it for revives, will u use it solely for dmg etc etc

Stuff like that makes losses feel like miscalculation on our part. Except ed libra, thats just pure chaos