I’m glad you mention this. From today https://www.404media.co/cbp-tapped-into-the-online-advertisi...

This shows a really fascinating dynamic.

In theory, the government doesn't need the ad exchanges which have very lossy information. They have access to the ISPs and cell service providers, etc, with a warrant. Dictatorships like China and Russia don't need ad network data to be police states, they just use the core phone, internet and computer data.

But in this case, the US gov are using the insecure private data as a run-around to the warrant process. This is definitely unfortunate, and I think laws should be amended to prevent this workaround.