The news stand price or subscription price for a newspaper wasn't a big chunk of the publisher's revenue even back in the 20th century. The big money maker was ads. Papers had a regional monopoly or oligopoly over a certain advertising channel. They could make excellent margins on classified ads when they charged people to list a used truck for sale, a duplex for rent, or an open job position that needed an employee.
They also made good (if not quite so excellent) margins on ads interspersed in the main body of the paper for department stores, auto dealerships, restaurants, and most other kinds of local/regional businesses.
On top of that, people didn't just buy the paper to get investigative journalism. They were also buying low cost content like the funny pages, movie reviews, weather forecasts, and sports scores. Even with limited competition for advertising, few newspapers in the 20th century could have turned a profit while filling their pages with nothing but investigative journalism. In-depth reporting is too expensive to make up the bulk of a paper.
Investigative journalism was a kind of expensive spice that gave zest to the rest of the lower-cost content. Newspaper owners took pride in it and tried to steadily produce it but there was no way to fill daily issues with nothing but investigation.
Craigslist killed the margins for classified ads. A million sources killed the newspaper's allure for delivering weather forecasts, sports scores, and other low cost information. Keyword and geo-targeted advertising on major digital platforms added fierce competition for print display ads.
The main thing people miss from the newspaper is investigative journalism. But investigative journalism, unbundled from cheap filler and high margin advertising, can't be delivered at prices most people are willing to pay. There are a few maybe-outliers like the New York Times and Los Angeles times that survive on a reputation for depth and a national audience. But the days of every mid-sized American city having a local newspaper or two with investigative reporters on staff has passed, unless someone can come up with a new business model.