It's so obvious that social platforms with business models based on number of ads/impressions like Twitter/FB are not incentivized enough to remove fake accounts, yet there seems to be very little public discussion or outrage about it. I agree with Mark Cuban here [1], they should do more to make sure each account has a real user behind it, even if it means less revenue. It's just the right thing to do.
[1] https://twitter.com/mcuban/status/957686987229618176