But it says that active cooling is only necessary for heavy workload, if you're fine with that then no fan required.
sure, but why pay money for functionality you're just gonna turn off (components, higher clock speed)
Phoronix tested the Pi 5 with and without the official heatsink, and without it peaked at around 90C (same temp my Intel Mac Mini from 2018 likes to hover around) and never throttled during benchmarks. You don't need to downclock, undervolt, or turn anything off to run fanless.
It's more energy efficient than the RPi4, so you should be fine if you're doing fine with any of their older products?