Respectfully, a large number of people rightfully fear for their lives, safety, and freedom due to being stalked or abused by a current or former partner. I have personally known several.
Using victims' devices and communications in order to locate, and then harass, trap, or attack them, is commonplace for stalkers.
If you can use victim's device, then Tor or any network level protection will not help you. If you can use their network, then just about everything uses https these days... and you still need to know their location to snoop in the first place. GP raised a good point of Tor not helping in those two cases.
Those are situations that people deal with, but suggesting they use Tor is not going to help them. (Apart from some very specific situations)
How many of these people are justified (by evidence, not merely paranoia) in thinking that Tor would circumvent whatever communications interception may or may not have been put in place?
And of those people, how many people have ever even heard of Tor, let alone know how to use it?
What fraction of domestic violence shelter occupants are paranoid rather than reasonably fearful? What fraction are paranoid, vs. those who are reasonably afraid of being spied on in general? Probably some, but I believe many have well founded reasons to want to be anonymous and in hiding.
I concede that tor is probably not a useful tool in general for these people. I meant to point out only that one needn't be paranoid to fear one's spouse.
Not to make too much light of a morbid topic but the idea of someone having a murderous yet tech-savvy ex who has methodically installed all sorts of elaborate digital surveillance measures in their former spouse's personal tech stack in service of premeditated homicide, sitting in a dark room somewhere, howling in anger upon realizing his murder plan has (somehow...?) been thwarted by said former spouse unexpectedly using Tor is pretty funny (because of how outlandish it is). "I almost got away with it too, if it weren't for you kids and that onion routing software!"
You are lucky to have not experienced stalking. It's not like some big nefarious plan, it's a relentless obsessed hunter who will use whatever the lowest-hanging fruit is to get to you. If they have IT savvy they will use that. If they are charming they will use that. If they are brutal they will use that. They don't need to be murderous obviously, just obsessed with you.
Knowing that there's one thing they can't get to you on is huge peace of mind. Not needing to think about your stalker, because there's no way for them to hunt you there.
Stop thinking about cloak and dagger shit and start thinking about things ordinary people could do if they had a psychotic obsession, and nothing better to do with 120 hours a week of their time.
Stalkers want to make it impossible to live a normal life. They try to make it impossible to go to work or school, to use phones, email, messaging services, etc. Already knew my contact info, and got new ones by asking mutual friends. Called the the landline and cell and work phone and hung up or heavy-breathed into the phone hundreds of times a day. Telco won't help with this or admit who's doing it w/o a subpoena, which I couldn't realistically get. They tried to get various online accounts, including employer provided, to be flooded/brigaded/spamed/banned.
You don't have to be a leet haxor to do social engineering, sim swapping, and other crying on the phone to customer service type of attacks on other people's accounts. You just have to be pissed off and risk tolerant.
Not saying tor is a good-fit solution to these problems, just saying that "Because your ex-spouse wants to murder you", and also you have a day-to-day practical necessity to find a secure, hard to block way to communicate on, or access, the internet is not actually an exotic problem.
tor-browser comes with other privacy-boosting features, beyond its method of talking to the network. That might make a difference too, if someone is likely to look at your browser history etc.
The second to last point is laughable since it's long been authorized in executive order that if the NSA stumbles upon information relating to criminal activity while searching for other stuff that they can report that info to the FBI.
Heck - FBI is allowed to do the same damn thing with the data they're given by the NSA. Y'know, the whole "backdoor search loophole" which amounts to laundering authorities across agencies to get access to data they wouldn't otherwise be permitted to have.
Because your ex-spouse wants to murder you.
Because you just escaped Scientology, or another cult.
Because you're a criminal. The NSA doesn't handle that.
Because you're a journalist talking to sources in the industry you're investigating.