There are definitely use cases for, say, a Wiki where you want the functionality of this module, but not for the Blog or Event content on the same site. I chose the Filter system because it has the most architectural support for the sort of text transformation this module applies.

Modules like http://drupal.org/project/better_formats undertake to make the Formats system more particular to those sorts of use cases. Failing that, this module could go in a different architectural direction, applying it's changes after the filter system is run and before the full content of the page is rendered. E.g., node post-processing.

Since this would require a lot more work to create and maintain (and make performant) I am recording this issue and marking this postponed pending significant need.