It will drop a PC to 0 HP, but the implications of dropping to 0 HP are very different in 5E vs. 2nd edition. In 2nd edition (and also I think in 1st edition, but I never played 1st edition) dropping to 0 HP kills you outright, and if you use the widely-used "Death's Door" rules it doesn't kill you until you hit -10 HP but it does wipe your mind clean of all spells and IIRC made you unable to fight or otherwise exert yourself for a lengthy period of time thereafter (a day?). In contrast, in 5E you can be back on your feet and fighting at full efficiency after a single bonus action spell (Healing Word) or even a completely free-except-for-gold usage of a Healing kit by someone with the Healer feat. At first level, there's still a chance the ogre could roll high and instantly kill you, but that risk rapidly fades as you gain levels.
Without insta-kill, it is impossible for the Ogre to win a fight against a party with two healers in it.
My point: looking at game stats in isolation, independent of rule changes, can lead you to believe in similarities which don't really exist.
Agreed, with some caveats. First, there is an instant-kill in 5e, and an ogre has a chance of doing enough damage in a single strike to kill a 1st level character in a single shot, and a much greater chance if it gets in a second shot against the same opponent. The main difference I still see, is that with the lower AC, the chance that the ogre gets to land a second hit is significantly lower.
Yes, they won't necessarily be dead. But if one PC is having to tend to a second that drops, that's half of your party out of the combat for that round. In addition, that character that's back in the combat is probably at much lower hit points, and is at a greater risk of being instantly killed.
With 1st level characters, if the ogre is attacking the same opponent, with a 50%+ chance of hitting, I'm guessing that character would last an average of 3 rounds against the ogre. If the PCs each have a 20-25% chance of hitting, then in theory only one will hit in a round on average. Which means the ogre is likely to be around long enough to potentially drop two of the PCs. Remember that if one of the PCs is dropped, and somebody goes to help, then half of your party is out of the combat.
Now this doesn't take into account special abilities, and magic, etc, but it also doesn't cover terrain and tactics either. So like I said it's not scientific, but it seems to imply that it is a bit weaker than earlier editions, and that bumping the AC back up would help.
Ilbranteloth