Does something like this exist? As far as I can tell, setting something similar up would require:
- A dedicated Lemmy instance for Mastodon tag-based crossposting (probably, since most existing instances probably don't want to clutter their instance with thousands of script-generated communities)
- Some kind of form on a site where users who want to follow a Mastodon tag that is not already set up as a Lemmy community could submit the tag they want added, which would automatically set up:
- A Lemmy community for that tag on the aforementioned instance, and
- A Mastodon hashtag bot that automatically crossposts all posts with that tag to the linked community
Guilty as charged. I'll say though, there are several legitimate reasons why one might want to do this. I personally use it as a substitute for Reddit's multireddit feature, by grouping community subscriptions across different instances by theme. As long as users use the same username across instances I don't think this practice should be automatically regarded as an attempt to sockpuppet. It that was the goal, the accounts would definitely not be using the same username across all the instances.