The only problem with your OP is the implicit insinuation that all servers, websites, or web services are equally vulnerable, and absolutely nothing can be done about DoS attacks, this is absolutely false. It is entirely possible to decrease the probability of a successful DoS attack, or to partially fend one off. Infrastructure capable of maintaining higher server loads or scaling automatically based on demand, having staff or automated systems capable of temporarily shutting down specific services or features being targeted disproportionately, automatically blocking traffic from certain sources, sending packets designed to trick the machines sending the queries to stop, working with ISP's to do the same upstream, or otherwise retaliating against a party launching a DDoS.