I'd take that particular article with a very large grain of salt. In the first place, it's almost 15 years old; times have changed (and the two breeds mentioned as rejecting becoming an AKC-recognized breed are now, in fact, AKC-recognized), the AKC contributes $1M per year to their Charitable Health Foundation, which funds research into canine diseases (genetic or otherwise). Secondly, it's very heavily AR-influenced (well, the numerous quotes from Michael Fox are a big tip-off) and as usual, promotes the myth that mutts are somehow healthier than purebreds (despite the fact that not only do many different breeds share the same genetic diseases, but a dog from two different breeds is thus at risk for the genetic diseases from *both* breeds). As well, it's quite a stretch to blame the AKC for the fact that some breeders don't do health screening and some buyers don't know or care about it; of course this was written before the advent of all the sham registries like ConKC popped up - as a result of AKC tightening their registration requirements.
Males should be bred around the age of two because most of the health testing is complete by then. After that, there really IMO is no set age that a stud can be a stud until. I have heard of sires 10 years old still doing it naturally, however by this age most are done thru frozen semen. Its not like there are health risks with a bitch who should only be bred from 2-5 IMO. The code of ethics says 6 but I would have a 6 year old be medically cleared before breeding her.
Here is the code of eithics as outlines by the ABC