does anyone know why it displays 'Not_compatible_with_d7' beside a number of modules in the User Points Contributed modules project after install as though it was a missing module even though they all say they are compatible with D7 (and they installed fine).
The reason you see that error message is that the content of the votingpoints.info file is the following one.
name = Votingpoints description = Rules integration for users earning points as they vote on nodes. With the rules approach, the node author can be assigned userpoints too. package = Userpoints dependencies = userpoints dependencies = rules dependencies = not_compatible_with_d7 core = 6.x
not_compatible_with_d7.module is reported as dependency of the module, and Drupal tells you that module doesn't exist.
What happened is that a Drupal 6 module has been committed in the Drupal 7 branch of the project; in this way, who wants to port the module for Drupal 7 can easily create a patch for the Drupal 7 branch of the project. The problem is with the script creating the archives containing the code of a Drupal.org project adds the like "core = 7.x" overriding the "core = 6.x" line added to the votingpoints.info file. This would cause Drupal to think the module is compatible with Drupal 7, which is not true.
The only workaround the authors of the modules found was to add, as dependency, a module that doesn't actually exist. That is the only thing that can be done, until the packaging script used from Drupal.org overrides the line reporting the Drupal version with which the module is compatible.