[maemilius]

This article was posted days before any of the links you've given.

According to the metadata for the site, it was originally published on 2018-10-14 and last updated 2018-10-16.

Facebook's own article about the feature came out 5 days after this article was published. So, at the time, Facebook _was_ being secretive about it. Aside from that one line, the entire article reads more like "this is new, I wonder what it does".

Lastly, when I googled "fbclid" the top 3 articles are completely unrelated to Facebook (but, then, I'm not in marketing so this doesn't surprise me) and the forth is this very article.

[soared]

That is fair, I didn't check when the author posted.

The first link (for me) when googling fbclid is the reddit post in r/analytics I linked to, which doesn't have a ton of info but gives more than what the author had. Though you're correct, it was posted after the author originally posted, and I can't fault him/her for not checking in again a few days later.

[ummonk]

They were probably doing an A/B test / phased rollout and didn't want to announce it until it was available to everyone.