Tbh I don't really know why you would use mence as a defogger; as an offensive defogger I would just go with the lati twins and if you want a defensive one mandibuzz (especially with aegi on the suspect ladder) or skarmory both work. They all get reliable recovery while poor salamence has to rely on wish (not necessarily bad but often times you'll prefer reliable recovery which helps with stuff like toxic stalling or else you have to run protect). I think one of the main selling points is that while it's for the most part outclassed by other dragon dancers, it does have some niches such as having intimidate to set it apart from altaria and dragonite to ease setup or moxie which makes it increasingly harder to wall every time it gets a kill and really discourages your opponent from sacking mons. Another cool thing about salamence is that it can go mixed which is pretty unpredictable and it actually has decent coverage.
Salamence has a pretty tiny niche but that niche still makes it viable.