Beetle ESP32 - C3 default board config

In the Wiki in “The first time to use”  https://wiki.dfrobot.com/SKU_DFR0868_Beetle_ESP32_C3#target_4
it is written that you should enable “USB CDC on Boot” 
The boards.txt the CDC on Boot is not on by default
https://github.com/espressif/arduino-esp32/blob/master/boards.txt#L6469
https://github.com/espressif/arduino-esp32/blob/master/boards.txt#L6478-L6481

Whats the reason for that?

On platformio i have to define additional compile flags to make it work. 
There are not lot of boards to compare too:
- lolin_c3_mini
- Adafruit QT Py ESP32-C3