We've discussed this in the past.

A forum can be split into so many divisions that there is no synergy anymore and people just visit for two minutes per day. A certain membership must be maintained to avoid this.

Each time a topic of WVO or Biodiesel is posted, it's on a separate thread that is quite obvious to everyone. If you're not into this topic, you simply pass the thread on by, similar to passing by a thread on an OM606 if you don't own an OM606.

I really don't see a problem with the current setup, however, I do see the benefits.