I would also disagree. I used to stutter severely, and as it slowly got better, the only way to be halfway fluent was to use synonyms. These little successes being more fluent with using synonyms, build up my confidence which in turn lessened my stutter overall. So I wouldn’t call it „unhealthy“ in the least. If it helps, it helps. Only that matters. Now I’m fluent 95% of the time.