The biggest problems are a) a lack of traffic and b) a lack of organization. There's the ranking system, sure, but there's nothing really promoting fighting. New faces come in once in a blue moon, but there's no structure to keep them around or to "remind" them to check in. You can "just" have a lot of fights if you have a good population and can steadily bring people in (even if they pop in and out) but if you don't, you need to have some kind of a lure. Just having a handful of people who sometimes, sort of, maybe fight isn't enough. It can be frustrating because it's kind of the work/experience or chicken/egg thing. You have to work to get experience, but you have to have experience to get a job. You have to have a population to have fights, but you have to have fights to have a population.

Gaia has a similar problem in maintaining a PERSISTENT community, but we also have the advantage of a lot of cross communication across several dozen individuals. Someone can clap their hands and shout "FIGHTING EVENT AHOY!" and people will crawl out of the woodworks. People message each other over Skype or Discord, or even text each other whenever it happens. 

Skalla and Rilla get a lot of immediate attention when they try to host something for a few reasons. A) They've been around a while, and havce run things in the past with varying degrees of success and B) like Melon said, they basically worked to build the Arena subforum from the ground up. 

I think the drop-off has a lot to do with the change-over from Old Guild to New Guild. Fighting, overall, has seen a decline since about 2011, which is probably a mixture of people getting older and the changing technology. Back in 2007, not everyone had Twitter, Facebook, Instagram, Vine, and a dozen mobile games on their phone. For a big chunk of the 2000s, the whole "forums" thing was a novel concept because most people didn't know about Usenet. You're always going to have roleplaying, but you can't just walk two paces and trip over a brawler anymore. You have to find them and then reel them in and get them involved.

Chat fighting has been dying a slow, ugly death for a decade. Forum RP has more sustainability, but only if people can commit to it.