The topic will only get locked or deleted if it breaks a rule itself. You find something wrong in the topic, you report it, and it gets what it deserves as soon as possible, but you cannot report the topic to get locked or deleted if there is spam in the replies but not in the topic itself. That is not how it works as far as I know. You can just report the spam posts within the pages of that topic.
Locking every single topic to stop spammers would simply be locking about more than 70% of topics in the entire forum as you can find spammers in almost every second post in the forum these days.