wrong, they can be controlled easily by the bios and software, accuracy of control is better with 4 pin fans, if your 3 pin fan has LEDs, they'll dim and turn off as the fan slows down. this wont happen with 4 pin fansOhh so these won't be controllable through software right? Only run at default speeds.
FWIW I was running 2 pin fans (even without RPM signal) on my MSI X470 with full fan control in BIOS. It kinda depends on your motherboard maker and the BIOS