"Facebook is a website..."

That is exactly right. I have no idea what "platform" means, but I know what "website" means. (Or "endpoint".)

Facebook was not always in the "news" business. The original website in fact had no "news" feed and initially users complained when they added this "feature".

The addition of "news" of the kind produced by journalists was added as part of this "feature" much, much later.

Facebook and the news media both sell ad space, but no one stores their personal photos and correspondence with the news media. If Facebook is, as Zuckerberg would claim, not a news organization, then Facebook cannot claim to have made any positive improvement on the quality of journalism. It stands to reason aside from "convenience" there is no benefit to getting news via Facebook's website versus the website of the news organization that produces it. To the extent Facebook manipulates the news that people recieve via the Facebook website, there could be negative effects.

AFAIK, the news media do not create online versions of their newspapers that (outside the control of the reader) automatically change what stories are presented based on the reader's identity. Though with the influence of Facebook's methods, it would not surprise me to hear that this was happening.

Whatever the case, certainly there must be a journalistic ethical principle that would point away from algorithmically manipulating which news reports are delivered to each reader, even if newspapers know the identity of each reader and what each reader has read in the past. "News", as in "newspapers", is the antithesis of controlled communications where not everyone recieves the same information, e.g., within a corporation.

Perhaps an analogy would be a library that knows the identity of its patrons and the items they have checked out in the past. It might be able to make predictions and manipulate which items each patron was exposed to when they visited the library, but it would seem against the fundamental purpose of a library to do such a thing.

The question to ask is what place does "news" (as in "newspaper" not updates on others' Facebook pages) have amongst people's personal photos and correspondence, the "99.9% benign user generated content"?

Why is it there?

Here is some background reading.

https://people.well.com/conf/inkwell.vue/topics/504/Brain-Ha...

https://www.wired.com/story/inside-facebook-mark-zuckerberg-...

"January 2018

Facebook begins announcing major changes, aimed to ensure that time on the platform will be "time well spent."

In fact, it was in besting just such a rival that Facebook came to dominate how we discover and consume news. Back in 2012, the most exciting social network for distributing news online wasn't Facebook, it was Twitter. The latter's 140-character posts accelerated the speed at which news could spread, allowing its influence in the news industry to grow much faster than Facebook's. "Twitter was this massive, massive threat," says a former Facebook executive heavily involved in the decisionmaking at the time.

So Zuckerberg pursued a strategy he has often deployed against competitors he cannot buy: He copied, then crushed. He adjusted Facebook's News Feed to fully incorporate news (despite its name, the feed was originally tilted toward personal news) and adjusted the product so that it showed author bylines and headlines."