..the thread about altcoins created by my friend has been locked for further comments after receiving up to 60+ comments within 24 hours...
So, this is your friend's experience? Why don't your friend that post this thread and aks about the reasons? In what boards are thread locked? Local or global? You may ask by PM to the moderator in that board, but remember that the chance is very small because the moderator has criteria why the thread must be locked.
Actually there are some reasons why a thread is locked probably:
1. There are similar other threads that have been created previously, so it is no need to create new thread again, better to continue or post on the previous same thread.
2. So many spams and junk posts that are in your friends' thread. So it is better to lock the thread. If you want to avoid the spam posts or junk posts, better to tell your friend that he should make the thread "self-moderated" because your friend can delete the spam or junk posts.
3. There are also probabilities where the OP only made a thread and he didn't make any reply again, likely making a thread and then leaving it at all.
4. The topic of the OP has been expired, not up-to-date or even no suit for this current.
5. If the OP made a thread with some questions and there are many similar and true answers given by the members by replies or quotes. So, it means that the posts have already answered the topic, so, rather than only there are repetition answers, better to be locked.
6. There are many out-of-topics discussions most on the thread.
7. Plagiarism (copy and paste from other contents)
So, ask your friend or analyze your friend's posts about them.