I'm guessing here, so no throwing stuff please. Is there not an element of 'Four wheel drive' here? By which I mean given the same engine output, less power is routed to each wheel (blade) and thus the slip angles are less, while
all of the power is employed usefully.
As the RR Merlin/Gryphon family got more and more powerful over its development, the Spitfire grew more and more blades on its prop, did it not? I'm not certain about four blades, although I'm pretty sure I made a 4 blade Airfix model. Ultimately the Seafire had five blade props to prevent 'deck pecking' and still be able to use the circa 2,400 hp available and later Seafires even had contra-rotating props, as did the Shackleton. In that case, probably because of spacing along the wing, structural strength and asymmetry.
Obviously drag is going to be a major issue with five or six blades, but the trade off must be that the increased power available can be used and still 'get a grip' on the air. A mighty engine like the Gryphon or the R4360 would simply cavitate on just two or three blades, wouldn't it?
Interestin question though.
Roger