@andy I'm not going to pretend I know the answer 100%...
However, here's how I view it.
LinkedIn is mainly about interacting with the LinkedIn community and growing new connections.
So, much the same as most social networks.
So, most people who are ACTIVE on Linkedin write "POSTS", not "articles".
Articles tend to have less reach within the LinkedIn community, they don't get seen or picked up as much.
However, "Linkedin posts", are much more compact, think 2-3 paragraphs, and these are SHARED more freely WITHIN THE LINKEDIN COMMUNITY.
BUT
Clever (sneaky) people, especially since the September 2023 HCU, used tools like ahrefs and semrush to check traffic stats regularly post-HCU for various platforms.
We ALL know about Reddit, and the "hockey stick" of that traffic graph for Reddit over the lasst 12 months is insane!!!
The same can be said for Linkedin (although both Linkedin and Medium took a little "hit" in February 2024, so just before the Core update, and Reddit even had 1000s and 1000s of spam comments removed around 19th March 2024, which also happened to be the last day of the SPAM update).
Anyway, all these platforms, have seen traffic increase significantly over the last 12 months, and especially 7 months (even with the slight dips this year, they're still in the 1000s and 1000s of % increase from 12 months ago).
So, back to these clever sneaky people, they noticed that Linkedin ARTICLES didn't really do well among the community, but due to the huge increase in exposure in the SERPs, it started to become noticeable Linkedin ARTICLES were ranking in GOOGLE).
So, they didn't care about the community interactions, making connections, or making their profile look "professional" (as long as they have a photo and a bio, which can be branded for your website and brand, so one paragraph is fine), they just wanted to write articles to RANK in Google.
And because of the increased authority and search engine exposure of Linkedin, their articles ranked WITHOUT a business page.
To me, it's much the same as Medium, if you want to get involved in the community and potentially earn through the community, then you need to do the "social thing and look professional on Linkedin".
HOWEVER
If you just want to "leach" off the domain authority JUST to rank in Google, then just make sure the articles are decent and you'll rank for the vast majority of well-thought-out longtail keywords (another clue, if you see a LinkedIn post or article ranking for a keyword, WRITE THE ARTICLE ON LINKEDIN YOURSELF), so you don't really "care" about looking overly professional and having a business page (as I say, having a profile photo and a shirt branded bio will suffice).
Is there a difference in terms of ranking in Google?
That I don't know.
I definitely haven't tested LinkedIn enough (although I do have two articles currently ranking, out of 5 written)