I remember my parents and teachers indicating this, and me and my friends thinking “then why do they trust TV, books, etc.?”

This is true; it was a almost a meme before memes existed, as to say "I saw it on the internet so it must be true!", as a way to teasingly highlight how non-credible it was seen at the time.

"Kilroy was here" was a meme before "meme" was coined. I don't think the phrase "before memes existed" has meaning.

Sure. Maybe better if I qualified it with "as they exist as we know them today"

Yes. "Anyone can write anything on there! There's no way to trust it." About halfway through high school they started letting us cite websites, and it was a big deal and considered very forward thinking.

yes. I remember boomers shitting on Wikipedia around 2004, but fast forward to present day and the same people would cite it.

On the internet no one knew you were a dog according to the Net Yorker cartoon