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.
interesting. I don’t think a profile would be much useful if it couldn’t be traced back to you, but as you say it’s possible to use writing style and grammar mistakes to fingerprint you. maybe use translation services that rephrase what you wanna say? or make intentional mistakes with some of your accounts? and have different accounts for different subjects, one for foss, one for politics, one for veganism, one for your job, one for your hobbies, one for more personal things, one for answering technical questions …
but yeah, do what your threat model asks for. but if you’re going to delete your account and leave, just know that it was a pleasant experience interacting with you and your content, ajz :)