Using Drupal as an app platform is a definitely trying to solve the problem with the wrong tool. My experience with this kind of thing is that these tools are

Using Drupal as an app platform is a definitely trying to solve the problem with the wrong tool. My experience with this kind of thing is that these tools are flexible enough that people can stretch them beyond their intended purposes, but it's usually rougher than just finding the appropriate tool. Specifically designed blogging engines become general purpose CMSes when people stretch and tweak them enough, and likewise people stretch CMSes into crude app frameworks, but you generally wind up fighting the tool about as much as building with it.