In my observation, most of highly established people and most of merit sources are ONLY active here in meta (and in local sections) for finding high-quality posts.
Your thought is wrong. Almost all local board have a merit source. And they are also meriting on others board also. Questions is about quality post. Even I am not a merit source but I visit Altcoin Discussion & Bitcoin Discussion board lately to help newbie. But problem is there isn't much quality post.
Only a few local sections don't have sources now.
Lafu already give you details where you can see more details.