Theee is little incentive to control an identity since there is NIP5 as soon as an account is compromised they can notify followers and make the NIP5 invalid on the old account. Followers will know almost immediately the user isn't authentic if it were a big name account where there was an incentive to control it.
Discussion
it goes beyond public posting. for example, don’t all your private conversations get compromised? which could be more devastating depending on the content on those messages.
Yes. Nostr is not a secure coms protocol. It's an open coms protocol. If conversations are meant to be private, they're best done with another protocol.