I will agree that even from the era of newspapers the concept of the newspaper having a certain bias and thus, a certain target group of people who have the same opinions and biases would buy the newspaper. “Yes Prime Minister” back in the eighties had an amazing 2 minute clip on that exact issue, practically confirming what you say that this has been happening for quite a few decades (if not forever):
The only thing that I want to add is that what has changed is the direction from which this operates (think the usual “the chicken laid the egg or the egg made the chicken” kind of thing). In the past, the newspapers, as a medium, knew that their audience probably had a certain ideology, but they also had some advanced level of understanding of things, just by being able to read to such a good extend as to buy the newspaper in the first place. This is how we had such articles as this, actually printed in newspapers in the 1950-1960 era:
This article is now tought in schools (were I actually was introduced to the author) and you might be surprised to hear that it is quite above the level of understanding of the average high-school student here, at this age (were we supposedly have a higher education), yet the newspaper that was simply called “The News” actually printed this in an era where kids used to go to school holding candles for lighting the way and still wrote on black slates. 
It sounds like a paradox since you would think that today we would be more educated and more keen to write and read (consume, if you will), such high-thought articles from the news, but that is not the case. The opposite has happened. With the advent of new media (radio, then TV and now the internet) the common denominator of the “news consumer” has lowered and lowered from the “educated class that can actually read” to the “utter moron that cannot even understand how percentages work during elections”, thus not only the downwards swift in quality and quantity, but also the reversal of the flow of news.
Once, the journalists wrote the news, based on what was going on, to satisfy the actual curiosity for useful news of a specific/linited target group of people of some educational quality.
Now that the target group is everyone, the base needs of the crowd to see its opinions reflected and stocked/supported, creates an unlimited market for the sea of non-news, opinion pieces and clickbait sludge, where there is almost no need for veracity other than a thin veneer of accuracy, just to avoid lawsuits for slander. And so we have fake … sorry … “alternative news” for everyone. From Flat Earthers to people that believe that drinking bleach is good for treating a virus.
So, yes, even “back in the day” a newspaper wanted to make money, but it couldn’t target the vast masses that couldn’t (or wouldn’t) read, thus they had to uphold a higher standard of journalism and quality of articles, else those readers would notice and the target group of readers would become even smaller.
Now, we even have Twitter for those with the attention span of an actual sparrow (and that is insulting to sparrows) and they are perfectly happy with “few words of outrageous snippets” and off they go, without even checking if that small snippet is even true or not, even though the we live in the “era of information” and they have the means to look for sources and double-check (an ability that the people of the newspaper era didn’t have). 
If you would like a suggestion, the 1985 book by Neil Postman “Amusing ourselves to death” explains the how and why of this quality shift in news, a lot better than I ever could. The book is mostly about the radical change the news underwent from “newspaper article” to “television show”, but you can extrapolate it for the modern internet era, since all that happened was turbo-charging that process to the maximum possible.
For a funnier, but oddly equally interesting read, Terry Pratchett’s “The Truth” is actually amazing on the subject of newspapers and how the public views the news.