I think that's just the downside of 1Password/Bitwarden's business model. The best they can do is explain the core features on the splash page, as you'd need a valid account to actually use the app in the first place.

KeePassXC is probably the closest to ideal. It could just use more info about what it does on the homepage, and change its name for better marketing. But the project states itself that their audience is "for people with extremely high demands of secure personal data management" so I doubt that would ever be addressed.