Nobody is telling you to break it, and nothing is indicating that this is necessary. We are asking you/somebody involved to please investigate the issue in order to find out what it would take to fix it, so that massively valuable functionality to the forum can be restored.
Surely, it would be possible, even low-effort, to do some basic inquiry to the guy who did write SMF - or somebody on their support forum - in order to figure out what it would take to remove the tagging permission-restriction. It's not like it's some obscure functionality that is likely to have a deep bug that no other SMF host/user has experienced for over a year.
Most likely a small setting that has been activated/reset by mistake, and can be easily remedied.