So there are a couple of interesting things going on here.
One, while Raise Dead says the spell automatically fails if the creature is missing vital parts or organs, Revivify lacks this clause. It is an open question, therefore, whether the spell actually functions on such a target or not.
Two, Revivify also lacks several other clauses. It lacks the clause in Raise Dead that resurrecting a creature causes that creature to take penalties because of strain. It can be cast on any creature that died in the last minute, willing or no, and it allows no saving throw! It is cast in a single action, instead of 1 hour. These are very odd, because Revivify is lower level than Raise Dead. One might say that this is counterbalanced by Revivify only working on those who have died in the very immediate past, but this is not balanced.
When I want to rez somebody, there's a very good chance it's because the party is currently getting its ass handed to it. In this scenario, all the other resurrection magic is useless; you can't rez someone until the fighting is over. But Revivify will get them back into the fight with no ill effects for the cost of one action, able to take actions immediately. This is beyond even the power of True Resurrection, a ninth level spell!
Finally, interestingly enough, by RAW, it doesn't actually matter whether it works or not. If it doesn't work, well, it doesn't work. But there is the absurd possibility that it does work, but the resurrected creature immediately dies a second time.
In other words, Revivify probably needs to be errata'ed. It's a third level spell in many ways more powerful than a 9th level spell. And in this specific case, it doesn't matter whether the spell works (unless some other game effect triggers as a result of the target coming back to life momentarily) - technically, the target is still dead after the spell is cast, although it may briefly have come back to life in the interim.
The most reasonable interpretation is the spell is supposed to include those restrictions, but the designers cut too much out of the description.