

Evidence, or it isn’t true.
Unrelated, but absence of evidence is not evidence of absence.
Anyways, your own statement:
Adtech relies on the OpenRTB 2.5/2.6 spec for tracking, you would have removed 1 identifier out of a hundred (one that isn’t really used anyway given SSAI is so popular).
Removing an identifier that is used. (1/100 = matters, “isn’t really used” != unused). This contradicts your other statements:
Yeah, multi-hop is pointless for tracking.
…IP addresses and multi-hop don’t matter…
Broad statements that don’t take into consideration the threat model of other users. Servers you connect to might not be using source IP in any way to track. You might be leaking so many other identifiers, that its completely useless to worry about multi-hop. But this is not true for everyone in every situation.
If its worth anything to you, the Tor Project seems to think multi-hop and IP addresses matter for protecting against tracking.
Asking for evidence wasn’t the issue, believing that the truth relies solely upon a discussion providing such evidence is.
You misunderstood. Some of your own statements say it matters and is used. Mandatory wasn’t mentioned nor implied.
I didn’t state they were the same. Tor uses “multiple hops” (you can find that string the the link I posted earlier). It is critical to the limiting of information seen by any single entity.
All that state can be removed. And the server might not be tracking that. Situations vary, adversaries vary. If you cannot imagine a scenario in which hops or IP address would matter, I would suggest doing some research.
Personal swipes mark the end of this discussion. I would suggest you to leave those out next time as It detracts focus from constructive learning.
This will be my last reply. You can also reply if you want (but I won’t see it).