One way to address this issue is to identify "edits by original responder that only update links" and exclude them from the edit limit. 

A possible mechanims to track this would be to store links in a separate table from the text of a post, so that the edit limit would only be decremented if the text of a post changed. (I don't know how much effort this would be to implement, as I don't know the physical data structure, but perhaps this will provoke thouhgt amongst those who do.)