In a single document, Rosette chains together mentions that refer to the same PERSON, ORGANIZATION, or LOCATION entity. These are called in-document coreferences. Titles, however, are not included in indoc coreferencing.
There are many cases where the same title may be used for distinctly different entities. Consider the following example:
President Trump met with President Marcon to discuss President Rouhani's statement.
The three uses of "President" refer to three different individuals. Obviously, they should not share a coref.
Titles are not included in coreferencing because there are many cases where the same title refers to different entities.