Add the option for a wiki.
I think you can transform ClassicPress into a wiki using a plugin. placing this feature inside core would go against the effort made to declutter core and move some features in core plugins I think.
Wiki Plugins as an example from WP repo
We are also trying something similar for our documentation site, using GitHub to manage changes to the content there: https://forums.classicpress.net/t/contributing-to-the-classicpress-documentation/2176
Definitely plugin territory. Just like e-commerce is.