Your example is a shell debugging session. You ran perf, checked iptables, inspected sshguard - all via SSH (or locally). The "observability tool" here is shell

Your example is a shell debugging session. You ran perf, checked iptables, inspected sshguard - all via SSH (or locally). The "observability tool" here is shell access to system utilities. This proves the parent's point: when the unknown happens, you need a shell.