To clarify my previous post, I'm totally fine with server-logs. As the 2nd-party to the conversation, the server
has to know who the request is from, and can log it. These logs can certainly provide a lot of value.
As you mention, I'm more concerned with tracking as a 3rd-party[1]. There is, obviously, at least some real benefit in these cases that would not be possible when only using server logs. It's probably a lot less than most people think. A lot of that data (or similar-enough data when measured in e.g. how much it benefits sales or makes marketing cheaper) can probably be found elsewhere.
If we knew what the core benefits (needs, not wants), we might (in an ideal world) even be able to have some sort of social negotiation where the data can be provided in some form (or an alternative, or by making sure the real social cost is covered properly).
[1] While the law currently doesn't work this way, involving a 3rd-party unauthorized should really be considered some new type of (criminal) wiretapping in states that require 2-party consent.