A lot of people consider .223 Remington to be an inadequate cartridge. I wouldn’t try taking an elephant with it, but with the right bullet and load it can certainly take deer and hogs.
But its use in that context always gets predicated with the statement: “with good shot placement”. Something like “yeah, .223 will work, but you have to have good shot placement”.
Is there any bullet that doesn’t work with good shot placement?
If you miss (the definition of “bad shot placement”), the bullet won’t work.
If you hit the deer on the left rear foot with a .45-70, while his day is going to suck, that still won’t “do the job”.
Any time you shoot you need to have good shot placement. The only way any bullet will do its job is to put it in the vital organs. I understand the point of the statement is because with larger, more powerful rounds, you can have a greater margin of error since it’ll hit the target with more oomph, do more damage, thus if you’re off you still have good chances of bringing down your quarry. But big-ass guns should not be a crutch for poor marksmanship.
I maintain that good shot placement should be a given and always in effect, no matter what you’re shooting.
Before I get all righteous in thinking we need to do away with this useless qualifying statement, is there any sort of situation where it’s a valid qualifier?
Stuff From Hsoi 
All shots take proper placement, but some rounds allow more leeway than others. My great-grandad used a .22 rifle (which I now own) for all his deer hunting, but he was able to do it by making head shots, which can be tricky. I’ve been able to drop my deer with both 30-06 and 44mag, and did not need head shots for either, but was able to aim at an easier target; the area behind the front shoulder. It goes through the lungs, and also delivers a shock to the body (my deer have always been knocked over as if being struck). I have never had to “finish” a deer shot that way, they expire within seconds. I wouldn’t take a shot like that with a .22 because it would probable just wound the animal, unless it managed to go between the ribs, and then wouldn’t cause as much trauma.