This isn't anything resembling what this FB post says, nor is there anything to indicate it is even talking about content that isn't on FB/Instagram itself.
My understanding is it's potentially illegal [1] to pay someone to post and not tag it as being an advertisement. Instagram added new transparency guidelines [2] that require sponsored posts to be created inside their platform [3]
[1] https://www.usatoday.com/story/money/2016/03/15/lord--taylor...
[2] https://business.instagram.com/blog/tagging-and-insights/
Yes, this is absolutely the FCC guideline. But this has nothing to do with FB asking for revenue for off-site advertising (which they don't do).
So this part of your comment:
> "Instagram (Facebook) updated their rules in 2016[1] demanding that off platform deals for sponsored content go through them so they get a cut."
is completely wrong.