The limit on one pending comment has the potential to slow or completely block a one-to-many discussion.

Say I post "I made the linked project. [Some cool facts about it]." and four people ask me questions. I start answering, and can't submit my second answer. I'm probably annoyed at this point. Repeat for the remaining questions.

Maybe the system could have a provision for submitting multiple pending comments on your own link or sub-thread to solve this.