I recently ran into an issue in using the Elixir Forum, which uses Discourse. I had posted a topic several years ago and wanted to revive it. In the interim, some new technology (liveview) has appeared, so I wanted to add a tag for it.
A moderator (AstonJ) tells me that there isn’t a way for a “member” to do this, so it’s necessary to send a message asking that the tag be added. So, the OP (let alone a topic reader) has to be fairly motivated to even find out how to approach this task.
This contrasts sharply with the situation during the initial posting process, where the user is required to include at least two tags and encouraged to add all relevant tags. Indexing systems need good data to work with; why not make the tag list easy to augment?