4x4x4 LED Cube resister problem

I am starting to do 4x4x4 LED cube (refer link)

I want to know why there are no resister needed at here.

Is it correct ???

The tutorial using 4 GPIO to control the shared cathode for each layer, using another 16 GPIO to control the anode. There are nothing and directly connect these 20 Pin to D0-D13 & A0-A5. I am using a this color LED, seems need ~3.3v |500x500

Is it add 4x S8050 between shared cathode and A2-A5 ??

I want to know why there are no resister needed at here

Because “The designer“ is an idiot.

Current limit resistors should be used. If not, the shared cathode pins are being tasked to absorb a lot of current and will burn out.

No resistors would be needed if driver chips with constant current outputs were used. Arduino pins are not constant current.

No mention of that made in the referenced link tho.