No, they really dont.
https://youtu.be/hr0qLLv3dKc
I can post GNs videos, or Jayz, or Pauls, or BitWit, or....
Really, take your pick.
When it comes to cooling, unless you are going to do a custom, multi-radiator loop, Air Cooling will beat AIOs short of thicker 360 radiators or 480 rads. And at the point where youre doing a custom loop.. youve got a lot more budget and arent looking at AIOs anyway.
It all comes down to (fin) surface area available to dissipate the heat. The only difference between liquid cooling and air cooling is the location of the fins. In the end, the heat is still dissipated by running air through fins. The available surface area is what really matters.
People who think that AIOs are better automagically are generally people who dont understand that you have to let the AIO get heat saturated. Temps 2 minutes after startup are meaningles.
Ill re-iterate that i dont think AIOs are “bad”, either. Just that they arent some magical fairy dust that is super-betterer because liquid. They have their place. They work just fine - as i said, for form factor reasons I used a Corsair H80i v2 in my rig, and it is perfectly capable. Keeps my OCed 8600K under 70c even at full (CPU+GPU) Aida64 test loads for 4+ hours (4.8ghz @ 1.21v)
But good air coolers cool just as well, and often better, and have their own upsides (no possibility of leaks, no chance of pump failure blowing up your CPU (though with modern CPUs this is less relevant, as theyll usually shut down rather than get cooked.). They can also be quieter in many situations (pump noise can be louder than fan noise sometimes).