About adding more merit source, some local boards and other general boards are very active with discussions and need merit source. For example, I don't see members getting merit on the altcoin discussion board, it's rare.
I'm glad you said it's rare, but that does not mean it doesn't happen. When topics of importance are discussed on that board, you will see them receive merit from those who get something from the topic.
If I recall correctly, I'm sure I have received merit a few times from the said board even when I don't post there frequently. It's just like the off-topic and gambling boards; all these places are rare for you to see posted being merited, but that does not mean that it doesn't happen.