These kind of thoughts are normal, but can develope into a subform of ocd called pure-o ocd

One of the very few at least. Around 90% of people have these kind of thoughts from time to time.

From a mastodon users point of view a Lemmy user behaves like another Mastodon user. For instance this is what my Lemmy profile looks like from mastodon:

Lemmy communities also behave kinda like users:

.

Even though they boost ( e.g. “retweet” ) everything that has been posted to the community. Be it a thread or a new comment.

The big upside of kbin is, that it, as you said, combines micro blogging and news aggregation. While Mastodonusers can interact with lemmy content users on lemmy can only reply to comments posted from Mastodon. We have no real way to send a toot (e.g. “tweet”) to mastodon deliberately.