If you access any website through Tor (or proxies) you're already more suspicious than the average user. If enough people cause trouble through Tor exit node IPs, it's only natural they get blocked.
Akamai published an analysis that affirms this:
https://web.archive.org/web/20170317110115/https://www.akama...
The relevant part:
> "we concluded that approximately 1 in 380 http requests coming out of Tor is verified to be malicious, while only 1 in 11,500 http requests coming out of a non-Tor ip were verified to be malicious. In essence, an http request from a Tor ip is 30 times more likely to be a malicious attack than one that comes from a non-Tor ip."
For a serious site, the cost of allowing passive reading is going to be ~0.
We occasionally had people upload child porn, they did it over the public internet and not tor, our lead counsel was a former US district attorney, his hobby was doxing the uploaders and providing all the evidence and information to the authorities in a "ready to prosecute" package. I forget the exact number but I think he got almost a dozen people prosecuted and jailed.
“Legit” Users likely block ads, are unlikely to enter their credit card numbers because of MITM shenanigans and it’s one of the few browsers that takes non-fingerprintability of its users seriously.