Granted, I don't hunt but have plenty of close friends who do.
.223 is legal in my southeastern state, where deer rarely get more than 150 lbs. Guys I know who use it have no issues whatsoever. You still have to get your round into the kill zone, all that matters after that is adequate penetration. With careful selection, there are a number of .223 rounds that can do that (again, assuming it is legal in your state). A .223 hit to the vitals that penetrates sufficiently beats a .300 Win Mag to the gut every day.
The only problem you run into with .223 is it's more sensitive to passing through brush and small limbs than other heavier projectiles. So you have to keep that in mind.
Yes, proper shot placement with "anything" will do it, but I've seen too many weekend warriors maiming game with their ARs and Mini 14s (in .223 that is).
It's not the AR's or the Minis, it would be the weekend warriors that can't hit the broadside of a barn.
I wish I could locate the info now, I think it may have been in
The Rifleman a few years ago. Anyway, on some game lands in the upper mid west some years ago it was found that most common cartridge used where wounded animals that traveled more than a few dozen yards was the 300 Win Mag. The theory being the people using that cartridge, in that particularly area, were using more gun than they could handle, resulting in a higher percentage of less than ideal shot placement when compared with lighter kicking calibers.