Apple News+ does something similar: https://www.apple.com/apple-news/publications/
There's another system like this: Your local library turns tax dollars into free books and articles, sometimes digital ones too. Worth checking. At the very least, many bigger ones have on-site (on their network) access to digital newspapers, journals, and magazines.
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I think it's the same reason we used to have all streaming on Netflix, but now every content publisher has their own streaming service. They make more that way, presumably, and have a branded product rather than relying on some intermediary that blends them altogether into an amorphous blob of "content".
They don't want to see articles turn into generic commodities the way movies, games, and music already are. The newspaper industry is barely alive as it is, and losing money and people every year... maybe they'll see another boost from the inevitable controversies of the new administration (again), as they did in 2016-2020, but short of that, it's kinda a dying industry with a lot of consolidation and reused/syndicated content.
If you don't want to pay, just go to APnews.com. It's where most smaller papers get their stories from anyway.
With unifying subscriptions you'd compete against Apple News Plus and Google Play Newsstand. Companies with big pockets.
You've answered your own question right there.
Follow the money:
Actual subscriber: $X per month
Paywall clearing house setup: $X÷Y per month (where Y is the division ratio of your payment to the clearing house vs. the clearing house's payment to the publisher) [1].
With $X being greater than $X÷Y, the publisher has an incentive to "go their own way" because they believe they will receive more revenue per reader that way.
[1] And the clearing house may even be worse, in that it may be some $X÷Z per read, where the Z divisor produces a value significantly smaller than $X per month.
A friend of mine has been doing business development around platforms for commenting and sharing with better incentive structure. In April we heard about this site
https://www.theverge.com/2024/4/19/24135011/twitter-alternat...
for the very first time (despite being people who are really interested in that sort of thing.) Then we knew it was going out of business so we both used it as much as we could while it lasted because, frankly, if our ideas were going to fly we'd need a platform with most of the features they had.
It was a refined and beautiful platform that looked and worked a lot like Bluesky and even though it attracted talk about current affairs it was not the right wing and left wing nuts you find on Ecchs or Mastodon respectively. (Maybe we didn't hear about it because they were careful in how they grew it) It was founded by Noam Bardin (founder of Waze) and backed by Andreessen Horowitz and Scott Galloway.
We figured if they couldn't do it there's no way we could do it.
Here's what I think happened.
Early on they were able to sign up second and third tier publishers for their universal paywall. My guess is that they planned to get their platform working really well (and did) so they could do a great demo (and did) and make a compelling pitch to first tier publishers. First tier publishers were not interested.
I'll challenge your analysis and say that an alternate business model could increase the total number of subscribers, but they would be right to be skeptical like you. A universal paywall could also be additive to conventional subscriptions.
The dirty little secret is that nobody wants to sell advertising free content in exchange for money because of this: one theory of marketing is that there are two kinds of people, (1) people with money and (2) people without money. Somebody who can't afford a subscription to The New York Times probably can't afford to keep a car in running order never mind buy anything non-essential. People who buy subscriptions are automatically qualified as people who are worth advertising to. There might have been an alternative timeline where, in the 1970s, magazines like Vogue were entirely free and supported by advertising but it doesn't really work because you need readers who have enough money that they can buy the stuff that's being advertised.
On top of that first-tier publishers have a terrible reputation for arrogance (in my experience confirmed for NYT), much of which comes from being at the absolute top of one particular social hierarchy. To me Bardin, AH and Galloway are startup royalty. To the managers of The New York Times they are the The New York Times and those other folks are just Noam Bardin, Andreessen Horowitz and Scott Galloway.