Closed Environment Air

I've heard (from urban grower) that closed environment is the best way of growing to keep out mildew/bugs with NO in/out fans. Conrolling temp with a chiller and humidity witha dehumidifier and c02 levels with a c02 burner, DO THE PLANTS REALLY NEED FRESH AIR?

HOW CAN YOU HAVE A PERFECT GROW ROOM WITH NO FRESH AIR EXCHANGE I DONT GET IT, ANYONE HAVE INFO ON THIS?

let me know ASAP

You just said it bud