Can you point out the topics you can't reply to?
The obvious reason is that the thread is locked by the topic starter so no one can post a reply in it. There are also other boards like serious discussion and Ivory tower where a newbie can not post.
Thses are some points I wanted to state out but then, the first reply nailed it. Well, there are some boards already pointed out that aren't open to newbies though, its got its way around it should you @OP be that desiring to make a post or comment on a particular thread or comment within a thread of that board. You could be a corper membership that puts you ahead of q fresh account or you can wait on your account to come of rank and then, you can freewill post in all boards of the section.
Again, ots of note that, these boards with restrictions and aces where signatures or campaign posts doesn't count are the least exploited or spammed on the forum. Don't you guys see it that way? What does this go to prove then...