That's unfair. I was in charge of anti-abuse for a dating site with millions of users and my gut reaction was "just 90%?".

The problem with anti-abuse at scale isn't catching the 90-99%. It is the remaining 1%. Have 10M abuse accounts with a 99% success rate and you are left with 100k spam accounts. That, and making sure you aren't catching too many innocent customers in your efforts.