For many people, the term “hacking” means that a criminal has broken through a firewall to get access to a network. The firewall is one of the easiest security concepts for people to understand, and often is thought of as the guard at the gate who provides entry based on a list of authorized visitors or other criteria. It helps that the term “firewall” originated outside of IT as a literal physical wall that was meant to prevent a fire from spreading, so the word itself was already in the public vernacular before the Internet was popular. ‘Firewall' is also one of the oldest internet security terms, having been formally introduced by academia in the 1980's. Because of the history and context of the term, it makes sense that people tend to think that the firewall is what gets “broken” in a hack.
Modern firewalls are much more than a gate that allows traffic in and out based on simple rules. The latest firewalls provide several other functions, such as DHCP, secure VPNs, Link balancing, and more. As business needs have evolved with the rise of branch offices, remote workers, and SaaS applications, the network firewall has evolved to keep pace and aggressively protect the network perimeter and provide the necessary services to enable the business it protects.