Most of the big consumer VPNs include "privacy" with an implication of anonymity in their marketing, so it shouldn't really be surprising
It is privacy with respect to your ISP. A lot of ISPs are pretty shitty. Some will rat out their own customers to copyright mongrels and threaten to disconnect you - which is important when there's a local monopoly.
Things you connect to or log in to are clearly going to be able to ID you at least with in the context of the login that you use regardless of what the VPN does.
I'm logged into HN through Mullvad as it happens. I usually leave it on regardless of what I'm doing because what I'm doing isn't my ISP's business even though I'm pretty happy with them.
"Not knowing who a user is" privacy may still be useful even if you don't have, "not knowing two users are the same user" privacy.
But what privacy do you think majority of people who not doing something badly illegal expect from VPNs?
Most likely these people just look to hide their torrenting, saying political shit on Twitter from employer and not share their choice of porn with local ISP. Also just adding one more layer between them and occasional scammer who can sometimes infer more broad geodata from their IP leaked from yet another database. Oh and now to avoid "Show your ID" page on the same porn sites.
It works well enough for this goal. Not everyone needs NSA-proof solution.
PS: Obviously more tech savvy people understand importance of hiding traffic on public WiFi, but I doubt average Joe the VPN user will buy VPN for this.