Soot? Its all real simple. More airflow means less restriction. Less restriction means more power due to more airflow. If you are looking for more power a stock filter is generally never the way to go. That pretty much sums that up
However More airflow/less restriction can also mean less filtering performance. Bigger micron sized holes let more particles through. More power less filtering.
Now you can have both. Lets say you have a filter made out of stock filter material yet there are more pleats which are deeper. More surface area to collect dirt and to flow air.
The oiled filters work better at filtering the older they get. Because they rely on the captured dirt in the oil to increase filtering ability...I know..Thats also reduces airflow.
The guy that wrote that article just kind of took a bunch of info and threw it together...He likely sourced it from another article he read
And aftermarket filter companies know all of this data. Its a give and take. I personally try to get as large a filter as possible. That helps most. And I have been staying away from oiled filters when a car has a MAF to rely on airflow readings as they can muck it up. And of course your oil may get dirtier quicker with an aftermarket filter that is same size as a stock one but flows better