We've seen the rise of machine learning come to fruition as the old school method of signature-based threat detection has lost its luster. With signatures, you're only as good as your last signature and won't catch anything new. There always has to be sacrificial lamb - someone that gets hit with a zero day or new threat - that spurs the cybersecurity industry to update what it deems as nasty and nefarious. Machine learning builds on what security practitioners have collectively learned and experienced with signatures (that methodology was an important stepping stone to get us to today) and helps eliminate many of the vulnerabilities that are inherent in signature-based methodologies.