When that idea was originated, the advice was more like:

"Don't trust what you see on the Internet. Trust instead what you read in a reputable daily newspaper, or Peter Jennings or Tom Brokaw on the nightly news, or BBC World News."

Today, the Internet, especially the part which is not trustable, has nearly finished killing most of the "trustworthy" news sources, by outcompeting them for ad dollars - by being way better at targeting ads (e.g. Meta) and by scientifically perfecting addiction (e.g. TikTok). What remains is mostly controlled by governments and has far from a perfect record of being fact-based and impartial.[1] There are a ton of independent people out there in good faith posting facts on the Internet, but we just agreed that we shouldn't trust what we see on the Internet.

So doesn't this become "Don't trust anything"? And doesn't that, in practice, get implemented as "Don't trust anything that challenges what you believe to be true"? This feels like a really, really bad change to our society - and I'd argue it's already completely happened.

[1] https://apnews.com/article/bbc-gaza-documentary-hamas-sancti...

Adequately implementing solves one problem (the making up a story because of a grudge), but creates a whole new set of likely much worse problems: how does one maintain a democracy / civil society? It's not just the trust of "social media" that you've eroded, you've almost certainly killed trust in traditional news reporting as well, especially considering just how much of traditional media is discovered via social media.

Effective democracy requires an informed voter base. Society requires its constituents to be invested in its continuity. Neither of those is achievable when we completely discard trust.