A quick glance at the page shows some features that normal "video organizers" don't generally have:
- Metadata scrapers (core + community ones [which, seems to be A LOT of them, see https://github.com/stashapp/CommunityScrapers/tree/master/sc...]) tailored to adult sites
- Videos also have N scenes, which also can be tagged
- Videos (and scenes) have "performers" and tags, rather than just one video file having actors/actresses and categories
- Videos/scenes have markers with tags
Doesn't seem like the feature set (except the scrapers) HAVE to be adult-only, but I guess there is a big audience enough to justify a niche application like this.