And if it were the altruistic Internet people they hired, the slogan/mantra could be seen as a reminder to check your ego/ambition/enthusiasm, as well as a shorthand for communicating when you were doing that, and that would be respected by everyone because it had been blessed from the top as a Prime Directive.
Today, if a tech company says they aspire not to be evil: (1) they almost certainly don't mean it, in the current culture and investment environment, or they wouldn't have gotten money from VCs (who invest in people motivated like themselves); (2) most of their hires won't believe it, except perhaps new grads who probably haven't thought much about it; and (3) nobody will follow through on it (e.g., witness how almost all OpenAI employees literally signed to enable the big-money finance-bro coup of supposedly a public interest non-profit).
For example, my impression at the time was that people thought that Google would be a responsible steward of Usenet archives:
https://en.wikipedia.org/wiki/Henry_Spencer#Preserving_Usene...
FWIW, it absolutely was believable to me at the time that another Internet person would do a company consistent with what I saw as the dominant (pre-gold-rush) Internet culture.
For example of a personality familiar to more people on HN, one might have trusted that Aaron Swartz was being genuine, if he said he wanted to do a company that wouldn't be evil.
(I had actually proposed a similar corporate rule to a prospective co-founder, at a time when Google might've still been hosted at Stanford. Though the co-founder was new to Internet, and didn't have the same thinking.)
Google's "don't be evil" was a way for them to say "we're regular Joes, just like you; we're not Microsoft, and we're not going to do bad stuff like they do".
