A forum has to receive a certain number of visits to be viable and healthy. If grouping things together that are somewhat related, but aren't exactly the same, increases views, then the possibility exists that someone who tunes in to read one topic might become interested in another topic. There are many forums on TradGang that are rarely visited by anyone, forums like PowWow that are visited by almost everyone, and forums like the Shooter's Form forum that could use a few more visits to be viable and healthy.
The problem with combining too many things together is that it makes it difficult to find things that relate to a topic you are interested in. It has never been my experience that having tuning topics, like FOC, in the form forum make it difficult to find posts that are more specifically related to form issues.
I have read and participated in tuning topics on the Form forum because tuning does involve form issues, maybe not all the time, but a form problem is always an underlying possibility when tuning is not turning out the way one expects.
I have often referred posts that specifically relate to equipment to PowWow, but have responded and will continue to respond to any post that may have tangential form related elements.