I think there are two ways to look at it, however. If you delete most of the pointless threads, newcomers and novices may want to try stirring stuff up. By showing how these trolls and bybs get shut down, you show that this board doesn't tolerate these kinda of people and their bullsh#t. We all have the right to our opinions, even if we don't always agree. There should be a certain level of balance.
On the other hand, some of these threads are inviting a fight and should be shut down, not necessarily deleted but closed. I know I can be really harsh at times myself but I have always believed in speaking my mind and if I see someone slinging some BS or making rude remarks, I'm going to call them on it. After all, it is only my opinion and that's what these boards are for....opinions.