And if that apparatus was used to prosecute US citizens for non-major crimes with any frequency it would come under scrutiny very quickly and you'd have politicians jockeying to legislate it out of existence and take credit.
Even if you take the parallel construction angle, no politician except maybe a dinosaur that is super-secure in their position (on the federal level that would be people like Pelosi, Fienstien, etc.) is going to tolerate that because if the other side can prove you knew then you're not going to have a job after the next election.
Obviously we need to remain vigilant but there are existing feedback mechanisms that generally prevent wide spread abuse.
To do parallel construction at scale you'd need to get the information into the hands of law enforcement in a plausibly deniable way. Doing that at scale would either have a predictable pattern (if every agency starts getting "anonymous tips" then questions are going to start getting asked) or would need to involve many people in order to plant the information in a more varied manner. Involving the recipient agencies themselves is not going to happen because two people can only keep a secret if one of them is dead so a cool million is going to be a non-starter.
A simple setup is to leave local PDs in the dark as they can always ask for the FBI's help for serious cases. Then the FBI gets access to tools provided by the NSA that look innocuous. For instance, lets assume the NSA snoops enough TOR to do packet correlation attacks. Imagine a simple tool where an FBI agent can enter an IP address or two, and get a list of "associated" IP addresses. Each IP can then be followed as its own lead. Once you've found the needle in a haystack, it's very easy to construct a false narrative of how it was found.
Politically, I don't know how it's possible to look at the current climate and think it will work against mass surveillance. Politicians will just shy away from directly confronting the issue. Whenever any spotlight gets close, the agencies will continue categorize it as national security / tough on crime / etc. The best political ally is seemingly the judiciary, and that itself will only slow things down.
They are two different philosophies, and thinking about how they'll play off one another is kind of interesting.
The US philosophy is to do passive surveillance and assemble the pieces after the fact, rather than mandating ahead of time requirements. Which means that US-based services will continue to be unhindered by such requirements, appearing "anonymous" to the rest of the world.
As more people globally are turned off by ID requirements, if they're able to flee to US services, then they're actually walking into a more sophisticated passive surveillance flytrap. USG will have ever more surveillance over other countries, without even having to clandestinely place taps.
Close allies will be given access through FVEY and the like, making that relationship even more lopsided. But allies' domestic law enforcement won't be, so they'll still be clamoring for more simplistic mandates requiring ID, further driving the process.
Except the dragnet surveillers pretty much know what they're doing is illegal, or at least in a very gray area. And odds are they generally only try to deanonymize people they consider a significant national security risk (with some abuse exceptions, like LOVEINT).
This is codifying forced attribution for everyone into law.
There's a big legal difference between the government working to unmask anonymous users and making it illegal to try to be anonymous in the first place. The latter is probably brazenly unconstitutional while the former is at least a constitutional grey area.
Not American internet users, for the most part. Note that those are at least justified by being connected to foreign actors, and that some of those surveillance apparatus are illegal.
And yet the US has all kinds of surveillance apparatus to de-anonymize internet users...