Some time ago there was dismay on Mastodon (and Pleroma ?) instances about data scraping. Before that happened there were privacy concerned people automatically deleting their own toots, limiting them for example to the latest toots for thirty days. With Lemmy things are different since Lemmy is a link aggregator rather than micro blogging, and Mastodon has boost option (Called replay with Pleroma ?). However deleting your older comments (but not posts) automatically would be really nice for privacy reasons.
See also my other new comment about issues
Posting a URL or an image can show a little bit about yourself, but comments and a posted question will show a lot more. Leaving the old posts like they are makes some sense since people can benefit from reading it without a very high chance of giving up your own privacy.
deleted by creator
Maybe not that bad idea: password protected communities 🤔