To be blunt, weight simply doesn't matter as much for cycling as it does for hiking. The weight is not going on your back and revolving weight matters more than the weight of the bike and parts (all of it matters obviously but the stuff you spin around matters more). If the bike is well made, the weight will be reasonable. It is possible for bikes and bicycle parts to be so light that they are prone to breaking. Weight is simply oversold as a criterion for determining quality.