Are they searchable and indexable? What made PHPBB and all that cool was that it'd turn up in search queries. As a hobbyist, this was an incredible wealth of information for me that has mostly dried up with the advent of walled gardens like slack, discord, etc. Some might point at BBS and IRC and say that those were the same, but I'd argue that they had lower volume, and less rich media, and I'd go one further to say…
There is talk about allowing public/discoverable servers to be indexed. I don't know when those plans might materialize, but it is very much top of mind for us that there is ever growing knowledge on Discord that isn't accessible via search indexes.
But how would it rank on google? At first there would be few to any links to content from discord.