This is a funny thing about FOSS licenses, and I guess a commonly known thing about the advertising clause as it relates to FOSS licensing. The wording in the GPL that causes this situation I believe is: "No additional restrictions may be placed on the redistribution of either the original work or a derivative work."

The intent of the advertising clause is to assert and maintain control over the software in the hands of the creator/owner; this is fundamentally incompatible with FOSS ideology, where anyone can fork and edit, and the leadership of the project is "de-facto" as in the eyes of a community rather than "de-jure". That being said, it is annoying.