Looking through the writefreely.org instances on their website, a lot of the links are dead or closed for registration. The one that is open and working is promoting a paid version. Is hosting a writefreely instance heavy on resources, attracting the wrong people or just not “cool” enough?
It’s extremely light to run, and very easy to install and upgrade. I ran one for just myself without open registrations. The only con is that the community (self-hostable) version doesn’t allow js due to “safety reasons” so in order to have something like comments for your blog you have to either perform several janky CSS hacks or adjust the source code yourself. The only reason I chose wf was because of federation, but I eventually switched to standard WordPress with the federation plugin and now have comments and whatever else I want.