better yet it makes it really easy to pinpoint traffic to a single person despite all other measurements to make this harder. I would guess being an IP transit provider would be a lot more beneficial for them otherwise with regards to the amount of traffic they would handle....

If you tunnel 0.0.0.0/0 or equiv through it, sure. You don't have to, though.

I just run my own VPN server on my cable internet. It allows all my roaming devices Pi-Hole access, and the same privacy as my cable internet.

And that is different from your ISP how? The distribution is less international?

There's nuances. ISP is whole household, VPN is device. ISP has a business, VPN might be interested in selling data especially the many free ones. You can VPN over ISP but can't hide VPN on VPN.