User blog comment:Kirkburn/Technical Update: October 26, 2015/@comment-8014223-20151027162933

"For performance reasons, the reply button will be switched off when a Message Wall thread reaches 500 replies. Existing threads that break this limit will continue to show normally, but new posts cannot be added"

Performance reasons? That 500 limit is an inconvenience, since the role plays I do are threads and they will and have gone over 500, plus I can't reply to someone on it if there is that limit.