break a lot of tracking by not making connections to known tracking domains in the first place
Whilst that's true, it is targeting the wrong thing. Your browser (and only
browsing) is sent to those domains just so a record can be made of where you were sent from - there is no other way to get that info. But now the ISP can SEE direct from your GET packet where you are going. Indeed, the ISP is actually sending you there so must know. There is no need for a spy domain workaround. You cannot block it (except by using a VPN, and the VPN operator will then be in the same position as your ISP - he knows exactly where you are going because he's sending you there).
The only issue now is that instead of the spy domains having the info, your ISP does (and the ISP info is far FAR better than that detected by the spy domains). The question is only: how much does the ISP charge for access to that info.
But, as alluded to above, the spy domains only capture your browsing stuff. The ISP will ALSO get everything: FTP, VPN, VoIP, ICMP, there is no destination and no protocol the ISP won't see.