Honestly, it fills the niche of not being LinkedIn.

LinkedIn is by far the worst user experience of any website or application I have ever used, one of the few that deserves the distinction of being both morally and technically broken. Not everyone is as drastic as I am, but in my circle it's universally disliked.

I use LinkedIn as a memory dump for job history and to keep tabs on old co-workers, but I actively try to avoid it otherwise. I didn't know they had a resume builder and wouldn't have looked, but it makes sense to have one. Even knowing they have one I'd be very interested to actually build my resume outside of it, but I don't know how representative I am.