How to get serial output in Arduino serial monitor

Arduino IDE 2.3.6 with recommended settings https://www.olimex.com/Products/IoT/ESP32-P4/ESP32-P4-DevKit/resources/ESP32-P4-settings-arduino.jpg
I can blink the user LED on GPIO2, but can't see any serial debug output.
I've just found that serial monitor works after I set "USB CDC On Boot: Enabled".
Why is it recommended to disable - are there any downsides to enable it?