Why We Need Anonymity on the Internet The Flying Frisby - money, markets and more

A few years ago I wrote a script called Four Murders and Some Funerals, about an old lady who is the victim of a terrible miscarriage of justice. Seeking revenge she murders one of the perpetrators (by accident - long story, but it works), discovers she’s a natural at bumping people off, does away with the other three, and ends up becoming a vigilante serial killer - righting wrongs wherever she finds them and usually where the law has failed. I still think it was a pretty good script, though it never got made - a bit like Miss Marple, only more savage and retributionist. 
Anyway, as a result of writing said script, I had to come up with a number of original ways by which an old lady might kill people: I had one person pushed down a lift shaft, another electrocuted in the bath, another shot and another poisoned. This all involved quite a bit of research, especially the various poisons. Should our heroine use cyanide, polonium, fentanyl or botulinum, for example?
For obvious reasons, I wasn’t quite comfortable googling all the questions I had, so I took to Tor, DuckDuckGo and internet anonymity. I’m glad I did because, believe you me, how to murder someone is one heck of an internet rabbit hole to go down. Before long I was reading about hiring Chechen hitmen and lord knows what else. 
Obviously, in the grand scheme of things, researching a script about a murderer is a fairly trivial use case for internet anonymity. But I don’t think the day is far away when your internet search history - which Google keeps forever, by the way, unless you take steps to delete it - will be taken into account for things like insurance risk, profiling, social credit score, by potential employers and so on. I don’t think several days researching how to kill someone reflects particularly well. 
Of relevance, one of my followers tells me that Justin Trudeau is trying to impose a law whereby police can retroactively search the Internet for ‘hate speech’ violations and arrest offenders, even if the offence occurred before the law existed.
But you don’t have to be asking questions about how to kill someone to want anonymity. You might be living under some extreme theological regime, asking questions like is there a god; or under a totalitarian regime, asking questions about freedom; or under a corrupt and incompetent regime, asking questions about vaccine safety. You get the point. Anonymity protects you. It limits the power that others have over you and the ability they have to control you. It enables you to protect your reputation, and stop things from being used against you, especially out of context. It gives you greater control over your own data and thus your destiny. 
But let’s say I did actually want to kill someone, and that I even researched how to do it, before deciding not to. The only crime I would be guilty of is thought. But if my search history can be used against me, it doesn’t matter if, ten years later I have moved on from the murder thing, it’s still there, and if the police or some activist decided to uncover it, I would, in the eyes of many, forever be guilty of murder, even if I had committed no such crime, beyond thinking about it - which, I bet, most of us have at some point in our darkest hours.
For me the most powerful use case is freedom of thought. Being anonymous is liberating. I’m sure that is why masked balls proved so popular.  If you know you are being watched, you are less likely to explore new ideas outside the mainstream, ideas which family, friends, colleagues or even society may dislike. These might be philosophical, political or theological ideas, scientific or artistic. We might want to express thoughts we otherwise feel unable to express. A lot of things, if judged from a different time or place, by people who lack complete knowledge or understanding, may seem odd or worse intolerable. Anonymity protects against having to worry about how actions are perceived and against  const