Comment by unethical_ban

Palo Alto Networks is one of several companies pushing custom versions of Chrome as enterprise security browsers doing exactly what you're talking about: holistic DLP/anomaly detection, URL filtering and content inspection in-browser. Presumably because it's closer to the malicious behavior, and network MITM is harder to accomplish with newer TLS and with decentralized workforces.

If Firefox had a more customizable, enterprise-feature-focused browser maybe we'd be seeing it used instead of Chrome? I don't know.