It's a valid point BUT........... remember, the exhaust fan is serving 2 functions: 1) smell control and 2) temperature control. The issue I'm facing right now is the fan is running at a very low speed (around 25% of max) because if I turn it up higher, it cools the room down to about 74 degrees. At a low speed, it is not cleaning the air properly, so it's more smelly. So I thought since I already own another 6 inch exhaust fan, I'd buy another Phresh Filter to fit and just scrub the air at 100% with this fan/filter and let it exhaust in the room, i.e. room scrubber.
So, this way, I can still control the exhaust air out and the room temperature while having a dedicated smell filter running 100% all the time.