Dribbble rocks and is pushing design forward. More visibility for our field is for the better, not worse.
Furthermore, hiring managers don’t care about other people’s problems (i.e. the problems solved in your portfolio), in fact they don’t even really know why they’re hiring you, yet. The sad fact is most hiring companies out there want you for precisely what they have in mind, which are common mis-conceptions about design as a job function. Dribbble at best represents the most aestheticly pleasing outcomes of a design process, but the more you match up with them the better it is for you interview-wise. That’s just marketing 101.