That video EsaT posted is a good watch on how cooler heat pipe transfers the heat..
I suppose only thing you need to worry about with air coolers is the fan bearing wearing out but I suppose that takes year year of use any way...
Here's trio of vids showing whole CPU cooler making:
https://www.youtube.com/watch?v=p71V6zLybig
https://www.youtube.com/watch?v=BBB2rChWxmE
https://www.youtube.com/watch?v=JKG1au3y-NU
I've had few very cheap and short 30 khour life specced Scythe SlipStream fans fail in some 4-5 years, but they started making "warning" sounds before stopping.
More advanced sleeve bearing fans last lot longer.
And fan failure wouldn't kill all cooling power and CPU would still operate well at idle/light load.
While in waterpipe coolers with their many additional degradation/wear mechanisms all eventually lead to catastrophic cooling loss of CPU overheating at idle.
And in case of pump failure it can happen instantly and without warning:
You just power PC on and before Windows has loaded fully CPU is throttling heavily and possibly even doing thermal shutdown.
Or simply shuts down if pump fails during say game play or other major CPU load.
Its such a big surprise that this method is so basic but effective and surprisingly cost efficient compared to aio coolers, and even with a mild basic overclock air coolers can still do a very good job and still hold there own.
And there was me thinking these heat pipes on these coolers was a cast iron rod that slowly transfer heat from the cpu 2 the fins and the fans attach cools not just the fins but the heat pipes also.
Iron is way poorer heat conductor than copper with only 1/4th of thermal conductivity. (and stainless steel just poor at 1/5th of that)
Even silicon used as base of semiconductors and CPUs/GPUs themselves is 50+% better heat conductor than iron.
Actually from solid materials diamond would be the best heat conductor.
And while waterpipe cooling is 18th century or something like that product, modern heatpipes are actually "space age" product.
They were developed for thermal management in satellites, which have major issues with surface exposed to sun literally baking, while shadow side is cooling toward absolute zero.
Along with absolute maintenance free and reliable operation requirement.
Nothing beats operation by the laws of physics in reliability...
Big dual tower heatsinks have way more surface area for dissipating heat into air than average especially slim radiators.
Even single tower heatsinks have lots of surface area.
For example sub £50 price Scythe Mugen 5 has 85mm deep fin stack.
Compare that to max 25mm thickness of typical radiator.