It's much more than that. It's a whole approach to architecture. The post I linked says it best.
> This incident emphasizes the importance of the Zero Trust model that Cloudflare follows and provides to customers, which ensures that if any one system or vendor is compromised, it does not compromise the entire organization. [1]
Authentication is a part of a zero-trust model, not the whole thing.
> No single specific technology is associated with zero trust architecture; it is a holistic approach to network security that incorporates several different principles and technologies. [2]
[1] https://news.ycombinator.com/item?id=26407364
[2] https://www.cloudflare.com/learning/security/glossary/what-i...