> It’s only a tool of oppression if you have a government prone to abuse and without constraints.
Untrue for three reasons.
One, it's a spectrum, and where you are can change. While the current US government is pretty bad, they're not rounding up citizens based on their race and throwing them into internment camps right now. But they have in the past, so let's not leave them anything that helps them if they decide to Be Evil again eh?
Two, there are different governments. Suppose the federal government is bad but not heinously bad and the Colorado government is pretty good but the Mississippi government is corrupt and racist and oppressive. Create the system federally and you're handing it to Mississippi officials to abuse, whereas they couldn't create their own because free travel between the states is constitutionally protected.
Three, it's not just governments. Create something like this and corporations will use it. Then all you need is for the government to fail to stop them, which is the status quo.
> In 2024, however, all not having one means is that they use software to link them – the context for this story is the huge industry doing that for all kinds of data, and they don’t mind having to link a couple of different identifiers.
The single identifier is what enables them to be linked -- it's why the surveillance apparatus keeps pushing it on us. Without it you have to speculate and will commonly get it wrong. If someone is signed into Google and then signs into their bank, does that mean they're the same person, or just two people who use the same computer?
If you pull an old PC off a skid destined for the recycler and use it exclusively for buying things on Amazon (which inherently has your shipping address), and use a different machine for social media which you never use for Amazon, a single identifier would still force you to associate the two no matter what measures you use to separate them.
It is important to preserve the ability to keep them separate.
Also notice the form of your argument: Things are currently bad so it's fine to make them worse in a way that's sticky and hard to undo. Maybe instead we should make things better?