“But why would this exact oversight still exist even though it should have been patched 4 years ago?”
CVE-2024-6778 and CVE-2024-5836 let a malicious Chrome extension run any shell command on the host with a little user interaction. The route went through chrome://policy/test and a DevTools bug Google fixed four years ago, except the fix exempted Page.reload requests. Google rated it high severity and paid $20,000. The sandbox held everywhere except the exception written into the patch.