Seems similar to the idea that simply won't let newbies and juniors to open a topic, only in selected threads (kind of newbie jail for topic opening)
Allowing only 100+ merited members to open topics would make the price of these accounts higher.
Also, imagine that there's a really good ICO that wants to advertise on the forum, but without an account with 100+ merits they have no chance to open their thread... (I know there are really a few of these kind of ICOs that are not scam/spam, etc...)