[burfog]

Not every influencer is making income that way.

Facebook is surely able to identify people with significant influence who aren't all that famous and who don't make any money off of it. Approximately, take the top 2% but excluding the top 0.01% to get these users.

Together they have huge influence, but mostly they aren't well-known. Their absence would have a huge impact but might not be noticed by an outside observer.

[mdoms]

If you're "not all that famous" then by definition you're not an influencer.

[burfog]

You can be, to a degree. There is a long tail.

Targeting the top influencers would be too obvious. There are a lot of minor influencers that add up to quite a lot, being in total very important. Facebook knows who they are.