Why would you violate your users' privacy just because of the network they are using? Many activists use sites listed here, including ProtonMail, Keybase, DuckDuckGo.
If you're so happy to help USA law enforcement without a subpoena it's a very good thing you didn't build Facebook or Twitter.
I'm not trying to be a dick and you're obviously free to do what you wish (in case you wonder, I have not downvoted you). But this attitude has absolutely ruined the web. Despite all the improvements in web technologies, browsers and even bandwidth, I have noticeably more difficulty consuming good information today. This is 100% because of lax attitudes to user privacy.
A few months ago, I had someone tell me on the programming subreddit that, while they were very concerned about privacy and Google Chrome, they tried Firefox but went back to Chrome because (and I am not making this up) the font kerning in Firefox was slightly suboptimal in certain situations.
That's what we're fighting against. This was someone on a technical forum who understood the privacy issues at play. But they valued their own privacy so little that they were willing to trade it for slightly improved font kerning. In short, I worry that we're well and truly fucked.
I think what you're really seeing is how much people value a good user experience, not how little they value privacy. Killing it on the UX end has always been a thing that OSS projects and software has struggled with and lack of growth there is, IMO, part of what has gotten us to where we are.
Even if they had your IP address, they would not be able to track which sites you are visiting on the onion network anyway. You could just be visiting the CIA's Official Onion Site.
I don't know how someone technical could think the FBI cares about some random IP addresses visiting dark.fail. Do you also think the FBI uses their VB.NET GUI to cyberhack-backtrace this IP address list to arrest people for the pre-crime of looking for DDG's/BBC's .onion site?
Having a list of people who visited the site (possible via DNS records) is definitely a way to drastically narrow your suspect pool. Now you don't need to be a global passive adversary - you just sit on the links used by the "bad" people.