VPNs use the perimeter-based security model, which has been declared faulty by NIST.
https://www.nccoe.nist.gov/sites/default/files/2022-12/zta-n...
Line 259:
"It is no longer feasible to simply enforce access controls at the perimeter of the enterprise environment and assume that all subjects (e.g., end users, applications, and other non-human entities that request information from resources) within it can be trusted."
A VPN has security at the gate, aka, it keeps people out of the network perimeter. The assumption is that if someone gets within the perimeter, they passed most checks and can be trusted. Or, if something is already within the perimeter, that entity is to be trusted.
Insider threats are very real. Negligent/malicious employees cause damages. BYOD stands for both Device and Disaster. Supply chain attacks work through ways that the perimeter cannot defend against, and that is why the National Institute of Standards and Technology calls for a shift away from the perimeter-based security.