Originally Posted by
kbarch
It's not a requirement, it's the manufacturer's recommendation. Presumably the people who buy it are looking for the best, and expect it to stay that way. Like any, it will stay it's best longest if it isn't abused by hot water, harsh chemicals or excessive spinning and wringing (stretching). Any and all knit garments made of lycra and polyester are subject to the same damage given the same treatment. They all get dingy and worn out, and they all eventually relax, which can be a problem for modest guys. But if none of that is an issue, and you look at jerseys and bibs like expendable commodities, feel free to use hot water, high-speed spin cycle and put them in the dryer with your sheets and towels. They'll all survive for a while, more or less. But if someone is going to pay a lot for a garment, it's totally appropriate to recommend that they take good care of it.
By the way, while I don't know if it's the case with Assos, sometimes because of the way a garment is carefully cut and constructed, machine washing, wringing and such can sort of "break" it, and it won't conform properly afterwards - once a seam is twisted, it can't be straightened. Sure, it's completely wearable and will last just as long, but that wonderful fit you paid so much for is gone.
Of course cycling clothes are expendable commodities.