If you think OS X's approach has done away with it, you're wrong. Maybe you've found it a worthwhile tradeoff, but flattening each application's dependency tree is still a tradeoff: you get truly independent applications, but you pay for it in duplication, the costs of which are well enumerated in binarycrusader's post. Maybe you mostly don't encounter those costs. Maybe you even believe most people mostly don't encounter those costs. But they do exist.