DT's CommentFormatter performs various DOM transformations such as
- Adding <span>s to mark comment boundaries and store comment metadata
- Marking the page as modified with an HTML comment
- Adding a subscription affordance to the header (future)
- Adding thread metadata to the header (future)
1 & 2 can be mangled by the transformations applied MobileFrontend's formatters. As DT tries to do transformations in the ParserCache, they will usually be run first.