Hi!
If you are referring to posting a comment or question in a thread in one of the *Photo Only* libraries then yes, you are not allowed to comment. Those threads are all clearly marked, however, a lot of people still continue to post questions or comments, even members that have been here for years. Sometimes people don't seem to notice that there's literally no other commentary in those threads.
Reminders are sent and the post is deleted. if we only delete the post, the member may not notice and continue doing it so an automated reminder is sent. I'd guess a dozen are sent/day for that alone, it's not considered a bid deal or anything major.
BTW those threads are photo only so people can find the resources w/o wading through pages of comments like in the main forums where comments and questions are welcome. The libraries are specifically photo resources.
HTH!