this is how subdomains are supposed to be used. gTLDs are marketing bullshit...

you deploy an application within a domain, it gets a subdomain wiki.chapo.chat is fucking win....all you need is the mediawiki software, database, and webserver, and based on what I've seen of this site, like, maybe a medium instance in any cloud if users are patient. The same can be done for any open source clones of popular services.