The benefits of creating quality topics is very simple;
1. You'll gain more knowledge.
one could argue that you should already have the knowledge before starting the topic and share that knowledge not to want to gain it after the fact. specially if it is a guide topic. i sometimes see such attempts that ends up being more misleading than being helpful.
Other users that reply to your thread and shares information will let you learn the things you missed on that topic. So I indicated that we'll gain more since learning is non-stop.