If a user has less than 50 reputation, it is known that they cannot comment on posts other than their own.
I've been in a situtaion, (this applies to the wider stack exchange interface) where I have been writing an answer to a question and the page has been commented on by other users. In a attempt to get the most up to date information, I go to click on add / show X new comments. But I can't.
I get the feeling this is a result of having less than 50 rep and so the comment feature is disabled but I don't want to comment, I just want to read the updated information as its coming in without have to reload the page and lose the answer I'm working on.
Now that I have more than 50 rep (just) and I can comment on other posts, the problem no longer exists.
Can someone else with less than 50 rep confirm this? I've seen in on StackOverflow, SuperUser and Electrical Engineering so far.