Print media does have more costs, but its advertising also costs more. Print also has subscriptions/purchases to actually get the material in addition to the advertising it contained so they have 2 revenue streams, allowing the advertising to be simpler and not carry the entire cost. And it still wasn't a great business model with many outlets just breaking even.
Regardless, there were never "millions" of advertisers or publishers like we have in digital which is why selling direct does not work, unless you only want the top 1% of sites to make any money...
And that's the biggest and best publisher there is, which goes back to what I last said: even if the high-end pubs do it, mid-tier and long-tail pubs definitely couldn't handle 1st party ad serving and thus would not be able to make any money.