Yes, this specifically what I'm talking about and it depends on use-case. If you're developing, say, a site that allows users to list items for sale, it seems to me that it makes the most sense to create a custom admin section for the user as part of the frontend. That way it's easier to mimic styling and it's a lot easier, it seems, to use the api to create all that's necessary for that type of user to edit and maintain individual settings without dropping them into the PW backend.
I wasn't clear with my Wordpress remarks so I'll go at it from another angle: the development of the WP REST API has excited developers for many reasons, among them being the ability to code custom backends for users that don't require interaction with the standard WP dashboard especially for reasons of styling consistency and unecessary complexity. Much easier to do a custom admin using the new api.
Of course PW already has a great api and I'd suggest that any site that is allowing users to create accounts and user-specific content (such as ads, personals, subscriptions, products, forum posts, etc.) a custom backend with identical styling to the frontend is the way to go. The admins and developers can use the PW backend for site management.