I think there was never some mythical golden age of pre-internet quality journalism, to be honest. I frequently read newspaper articles in supposedly respectable outlets that are not about breaking news yet are still riddled with serious flaws or biases, sometimes outright falsehoods. This problem becomes a hundred times worse when exploring their opinion columns or editorials. If "journalism school" (whatever that is) tries to teach journalists to be unbiased fact checkers then it's not done a good job.
I think the internet has been a massively positive thing for news in general, as it so quickly allows people to do rapid fact checking, get access to contrary opinions, see comments on the articles and so on. If your dad doesn't do those things he probably wouldn't have been more informed before the internet, he'd have just quoted you other one-sided sources too. Fact checking things you want to believe in takes discipline and commitment, it isn't something that was broken by the internet.
No, you had something far more dangerous: plausible-sounding false claims that were repeated without any challenge and therefore ended up being believed without question by a far higher percentage of the population. At least with the Internet, you can find refutations of false claims if you care to look.
You're forgetting about the Yellow Journalism era of the late 19th century.
Or the role of newspapers like the Boston Gazette during the lead up to the American Revolution, that mostly served to turn the populace against English rule.
Or the mass publication of seditious libels during Restoration England. If you want to talk about whacked-out conspiracy theories, you should see what was published in the 1660s through the 1680s. Popish Plot anyone?
The idea that journalists should be unbiased is a very, very modern one.
What I'm really curious about is what changed between the era of yellow journalism and the mid-twentieth century. I absolutely agree that people hearkening back to print journalism as a time when everything was fact-checked and reliable are mistaken, but it really does seem that journalism now is more sensationalist than in the recent past, just not the distant past. That means that print isn't the answer; there's something else to a society that makes its reporting either good or bad. What is it? Corporate power? General partisanship?
I've read that some posit that the switch to a subscription model in part effected the decline of yellow journalism. The subscription customer's purchase decision is potentially less driven by in-the-moment attention-grabbing and more by characteristics like informativeness and accuracy.
I think the internet has been a massively positive thing for news in general, as it so quickly allows people to do rapid fact checking, get access to contrary opinions, see comments on the articles and so on. If your dad doesn't do those things he probably wouldn't have been more informed before the internet, he'd have just quoted you other one-sided sources too. Fact checking things you want to believe in takes discipline and commitment, it isn't something that was broken by the internet.