[disgruntledphd2]

If I had to guess, because their self service tools suck and they haven't invested in agency relationships.

If you want a successful internet ad business you need to do one of those, but preferably both.

That being said, it's wild to me that Twitter never managed to build a DR (i.e. selling clicks/conversions) business, so maybe Reddit is equally as badly managed (which again, is really surprising to me).