They once deleted my account, because the email address stoped working and I forgot to change it. I thougth I'd had a backup, but then I realized it was without tags and comments. Since then I mistrust such services, better to store stuff on the own devices.
In my humble opinion, you learned the wrong lesson. The right lesson is "keep (and verify) regular backups", doesn't matter if it's a remote or local system. Obviously, if the remote service makes that hard, you probably shouldn't use it, but Pinboard isn't one of them.
