I agree with your explanation of how Tor works. However, respectfully, TOR is used extensively for both legal and "dark" purposes - which both benefit from its intended purpose of anonymity.
From Wikipedia:
Usage
Further information: Dark web
Tor enables its users to surf the Internet, chat and send instant messages anonymously, and is used by a wide variety of people for both licit and illicit purposes.[49] Tor has, for example, been used by criminal enterprises, hacktivism groups, and law enforcement agencies at cross purposes, sometimes simultaneously;[50][51] likewise, agencies within the U.S. government variously fund Tor (the U.S. State Department, the National Science Foundation, and – through the Broadcasting Board of Governors, which itself partially funded Tor until October 2012 – Radio Free Asia) and seek to subvert it.[14][52]
Tor is not meant to completely solve the issue of anonymity on the web. Tor is not designed to completely erase tracks but instead to reduce the likelihood for sites to trace actions and data back to the user.[53]
Tor is also used for illegal activities, e.g., to gain access to censored information, to organize political activities,[54] or to circumvent laws against criticism of heads of state.
Tor has been described by The Economist, in relation to Bitcoin and Silk Road, as being "a dark corner of the web".[55] It has been targeted by the American National Security Agency and the British GCHQ signals intelligence agencies, albeit with marginal success,[14] and more successfully by the British National Crime Agency in its Operation Notarise.[56] At the same time, GCHQ has been using a tool named "Shadowcat" for "end-to-end encrypted access to VPS over SSH using the Tor network".[57][58] Tor can be used for anonymous defamation, unauthorized news leaks of sensitive information, copyright infringement, distribution of illegal sexual content,[59][60][61] selling controlled substances,[62] weapons, and stolen credit card numbers,[63] money laundering,[64] bank fraud,[65] credit card fraud, identity theft and the exchange of counterfeit currency;[66] the black market utilizes the Tor infrastructure, at least in part, in conjunction with Bitcoin.[50] It has also been used to brick IoT devices.[67]