It's kind of a hyperbole, granted, but most of our assumptions about disk access being faster rely on only one piece of software accessing that disk. With modern multi-core processors, pre-fetching and caching both at the application and the kernel level that assumption is quickly proven to be faulty.
10ms random seek is fine when you're only accessing one thing. But when multiple things are loading and alternating between locations it becomes significantly slower. Windows startup can be a pretty good indicator of this. I've got one system with an SSD (containing the OS) and a spinning platter drive for data. When I start it up, I have to wait for more than a minute before clicking anything or I end up with an unresponsive application for 3+ minutes. It still induces a quiet, resigned rage that such a powerful system can be nigh-crippled on boot.
10ms random seek is fine when you're only accessing one thing. But when multiple things are loading and alternating between locations it becomes significantly slower. Windows startup can be a pretty good indicator of this. I've got one system with an SSD (containing the OS) and a spinning platter drive for data. When I start it up, I have to wait for more than a minute before clicking anything or I end up with an unresponsive application for 3+ minutes. It still induces a quiet, resigned rage that such a powerful system can be nigh-crippled on boot.