While their account privacy policy is commendable, it isn't a proof for not collecting logs.

Even without personal details you can collect quite a lot of data - ip address that uses certain VPN account, which servers it talks to while using vpn, at what hours, at what intervals, also all the plaintext data exchanged between client and server. A lot of data that someone (who might already have your ip address mapped to your personal info, for example your ISP, or an online store where you shopped something before you turned on the VPN) would be willing to pay good money for. And companies like money.