I have to say that I dont fully agree with that. For the past two years I have never once trimmed or plucked a feather or even began to AI and had decent fertility. I set 6 dz eggs last year, the first 4 never hatched due to incubator issues, out of the 50 set, 37 that we checked were fertile and a couple we were unsure of just yet. After getting the issues fixed, ended up setting 34 more eggs, and hatched 28 to give me 40 chicks counting what the hens hatched and raised. BUT, I also agree with you because that doesnt mean that letting my birds breed naturally will always work. You never know when knowing how to AI or when plucking/trimming feathers will come in handy with this breed. (Especially the frizzles, they seem to have an extra layer of fluff.)
~Casey