I doubt many use this feature on a regular basis. Remember, most of what you post on Nostr is entirely public, so you are not seeing anything the user should not expect you to be able to see.
Discussion
i figured as much. i couldn't think of any reason to login using someone else's npub when i can just go to their profile except maybe see stats in nostr.band.
You can see what their follow feed looks like, which could give you some good folks to follow yourself.
i have been finding interesting people to follow in the replies. it is interesting to see who users regularly interact with. it has been working great for me. i have also found good people to follow through #asnostr !! ;)
Both of those are also excellent ways to build out a follow list.