The problem with wikis is similar to the problem with forums... it's not that they do not work really well, they do, but it's that the cost of running a single wiki or forum in terms of operational overhead and hosting costs is significant.

Dynamic user generated content is going to do two things:

1) it's going to result in you needing a database and a web server, capable of a few concurrent users (in addition to bots and guests) but likely sized to handle your spikes in traffic... i.e. over-sized, let's ballpark at $50 per month (people will argue some specifics, but in general this is indicative)

2) it's going to result in you needing to stay up to date, moderate new users, and manage spam... i.e. it requires a disproportionate time investment

and the content is likely crappy, you were just having shits and giggles and nerding out on some small thing that you got excited about... not quite worth those costs.

the solution then is a multi-tenant platform that distributes the ops, cost and moderation problem evenly across many sites, so perhaps the $ cost to you is $1 per month, and time is hardly anything.

but now you've got a different problem, now there's a central entity that "owns" the platform and likely helped itself to a license allowing it to use all of the content, monetise away and profit of the fandom of others.

there are anarchic platforms to counter this, but they're small and cannot be the destination for people to migrate to, and so we're stuck with either the high overhead, costs, and burnout of individual sites, or these crappy platforms taking their users for granted.

though now I wonder... what license is fandom content under? can an independent entity scrape it and start over?