We had a WP washer with "Magic Mix Filter"
When growing up, IIRC it was first washer Mother Dear had, and was bought when moved into the new house.
Don't recall Mama ever putting powdered detergent in dispenser, but like almost every other housewife one knew, detergent went in bottom of tub as washer as fillng, then laundry added.
Cleaning that brush filter was a royal pain. My WP portable/convertible (a later model) had bed of nails lint filter which was a decided improvement. One could whack on solid surface and that took care of lint.
Would imagine that Magic Mix filter wasn't so bad when powdered detergents were phosphate laden. But once things moved over to Zeolites and heavy amounts of washing soda can see where problems would start.