True, but keep in mind that just because these hidden services' true identities aren't known, doesn't mean they can't have a reputation.
If this search engine becomes popular among Tor users for example, and you follow a few news sites which focus on stories related to the dark web, you'll end up in basically the same situation as you are now with Google. (With the search engine losing the trust of its users if it starts behaving maliciously.) Same goes for other hidden services.
That's all technically true, but I doubt even HN readers really understand what that means. So let's compare...
If you open up a Google Chromebook and discover new sites by going to the default page which is a search engine also owned by Google, who a) because of the sorry state of CAs has implemented its own open source tool to watch the set of known certificates for any funny business that would signal a break somewhere in all that overly-complicated brittle technology, and b) is Google's bread and butter such that if they started mapping site titles/descriptions (which you've probably heard of out of band) to different URLs would lose their stranglehold on the industry, not to mention such an attempt would be reported widely in the news media... you can't know their names in advance anyway.
vs. an expanded version of the original:
If you are discovering new services via a new search engine released from an entity you've never heard of that maps page titles/descriptions of hidden services you've never heard of to human unreadable strings on an anonymity overlay for which phishing scams, covert site takeovers, and drive-by malware attacks don't make the front page of most news media... you can't know their names in advance anyway.
Edit: remove redundant adjective, clean up confusing sentence