Since Facebook banned them I've seen a surge in them on Twitter. Will be interesting to see what they do, and whether it contributes anything meaningful to their profit situation.
I'm actually glad Google are (at least for the time being). Whilst rogue ICOs and crypto-pumpers are still working their stuff, the market is much more akin to back-street gambling and since there are already regs on AdWords for unsavoury ads, this fits the bill.