Seems so but I also don't understand the Akonadi hate. When I still used POP3, mails appeared to be in the inbox twice but that was merely a cosmetic problem, IIRC. After migration to IMAP, I don't think I ever had problems. That said, I'm currently not using any KDE PIM apps for unrelated reasons (my main PC is currently running Windows and Thunderbird is so much worse than KMail).
Then you did not try everything. With Linux a fresh installation is basically never needed. Last I've checked Akonadi is just a cache, never the actual data.