system
A chat on subreddit /r/pcmasterrace
human
The AIO's are not really better then the cheaper quality air coolers.  Many times they on par with a Noctua air cooler that is 1/2 the price..  The 120mm versions are absolutely trash and shouldn't even be sold.
gpt
I'm working on an ITX mini build where the case requires a 120mm AIO in order to have  any actual airflow across the CPU. They have a use case in small form factor builds where nothing else works.