Less granular audience targeting forcing increased ad spend to reach a broader audience. FB really doesn't lose out.
If marketers make less they have less to spend. The less efficient they can be, the less they make, the lower the equilibrium bid ends up being.
Everybody has plenty of advertising channels to choose from. If FB suddenly gets more expensive to reach your target customers, the dollars will move elsewhere.
This data had a baked in 10-15% markup...so costs should actually go down for advertisers.