Headline is a bit misleading. While there are other factors and concerns in choosing and using a VPN, using one will absolutely save you from your ISP snooping on your web activity.
Generally VPN providers don't use residential ISPs, they buy transit from a transit provider. I can't remember ever hearing of a transit agreement that permits the transit provider to sell connection information.
Oh, not to mention the possibility of them blocking well known VPNs "to prevent piracy." Many open WiFi providers already do this.