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).