It wasn't just about "the truth", it was about how people could participate in mass communications: the newspapers had a lock on one of the main ways to do this. The internet gave us a new communications medium.
Many newspapers gave away most of the value in their advertising power to Google and Facebook, for free, because they just didn't understand how internet advertising was going to work.
Now they've decided to blame and shame their own readers rather than actually try to compete against other media for people's dollars.
But it's a good point. Classified ads were purchased by individuals or small companies usually. Now, the people things did with those, they do for free, or use some other paid service that's not affiliated with a news organization. Instead of paying for an ad in the "personals", people use dating apps (either for free, or they pay for a premium membership to get extra benefits). Instead of paying for a classified ad to sell their old car or appliance, they post it for free on Ebay or Craigslist or FB Marketplace, and in most cases pay a commission when they receive payment through the site. So basically, other services took this revenue stream away from the newspapers.