From my research I feel it varies by species as to what they can digest or utilize from the feather meal.I found studies that said digestibility was pretty much nothing on up to 60-70% from the Dr. Cecil quoted.
It is sort of like the PB phrase"it all depends"
Each study was with different fish under totally different conditions.
If it is used as the sole source of protein,then I agree 100% with you in it being a scam................but I also feel it has it's place in formulations for some fish.
