[hansvm]

I think a lot of people have been burned by inheritance done wrong.

With a lot of other techniques, if the implementation isn't perfect and you don't own the library you're using you still have a lot of power available to patch things up and make everything play nicely together. Inheritance mixes implementation details with your type checking, so in a lot of languages that can make it extremely painful to turn a body of almost-good-enough code into something that's actually usable.