What is the difference between the ISP knowing this and being a problem, but the VPN sitting with the exact same information, also knowing it?
I don't know if you're aware, but basically all sites on the internet use something called SSL these days. However, SSL is useless if you use a VPN that also provide DNS servers (which most do) - because the provider could listen in on all of your traffic by hijacking the handshake, DNS and traffic to and from any target server - making it much easier to create a user profile, because you're authenticated to the VPN.
Also, third party cookies are blocked in the mainline browsers by default, making VPNs even more useless.
Most if not all of the ISPs also use dynamic IPs, making it unlikely to be cross-site-tracked based on IP sources.
Additionally, 3rd party cookies may be blocked but cross-site are not.
Your VPN doesn't protect against squat when it comes to the agencies that might be watching. Hell it doesn't even protect much against marketers fingerprinting your movement around the internet. You leave a plenty big breadcrumb trail that isn't just IPV4.
Honestly VPNs have been a great marketing example of the last 5 years. You all buy something without needing it or knowing why t f you have it. Yes using internet without one is better. Why? It's cheaper for starters.Auth. faster! No relay slowing down your connection!
VPN best use isn't on consumer end. It's on orchestration end as another tool to guarantee you are who you say you are via another layer of auth.
The point of cyber security tools like VPNs is to limit tracking, data sharing and reduce the potential for malicious actions to be taken against you.
You can't honestly say not using a VPN is better than using one. What's the alternative? Unencrypted web traffic? Your ISP harvesting your web data and selling it? Exposure on public networks?