In this case it is because off-topic, and I agree PM moderators is not the smartest move, what is deleted will likely remain deleted.
theymos emphasizes about off-topic there:
Off-topic replies have become a big problem. From now on, I will be deleting such replies without notice, forum-wide. If your replies disappear, this is probably why.
All replies must respond to the topic's original post in some way, even if they are replying to an on-topic reply. If your reply has nothing to do with the topic post, either add some content that is relevant or create a new topic.
Please report off-topic posts as soon as you see them.
Furthermore, I believe that whenever we get deleted messages, we should stay back and re-consider about potential reasons why our posts deleted. There are some reasons to do this, because if we get deleted posts so many times, maybe we are spammers, and our accounts might be nuked or temporary bans. For higher level users, they rarely fall into such cases, but it makes sense for newbies, whom simply come to the forum, and even don't know all forum rules. Therefore, I support the OP by open the topic and ask for help.