If you want to talk money then it is in businesses best interest that money from their users is being used on their products, not being scammed through the use of their products.

Secondly machine learning or algorithms can detect patterns in ways a human can't. In some circles I've read that the programmers themselves can't decipher in the code how the end result is spat out, just that the inputs will guide it. Besides the fact that scammers can circumvent any carefully laid down antispam, antiscam, anti-virus through traditional software, a learning algorithm will be magnitudes harder to bypass. Or easier. Depends on the algorithm