Better title: VPN services only provide weak privacy, and can see your traffic as much as any other ISP.

They are good for escaping an ISP that messes with your traffic and injects things or a country with soft Internet censorship (where soft means they won't arrest you, they just block stuff arbitrarily). They're not anywhere near what Tor or a similar system will give you -- but that comes at a cost of speed and complexity.

I also agree that the best VPN is one you set up yourself on a VPS that you control. Not everyone knows how to (or wants to) do that, but if you can it's great. One of the cheap tiny VPS offerings from Digital Ocean or Vultr.com is great as a personal VPN endpoint and can also double as a personal web server, backup repo, etc.