Depends really on the perspective you look at it from. That post is from the visitor privacy / privacy regulations perspective. If you use GA full on, you will get some advantages such as storing cookies on devices but if you either make GA "privacy friendly" (enable IP anonymization, disable user-ID, disable cookies etc) or ask visitors to consent to being tracked you will get less accurate numbers than our method.

We haven't noticed any issues with VPN usage as still you need people to use the same IP, same user agent and visit the same domain all on the same day to be counted as one with us.