Comment by Gigachad
There are countless routers in between you and your destination which you can't audit anyway. End devices long since consider the routers to be compromised and have everything verified and encrypted in transit. So unless your router is participating in a DDoS or mining bitcoins it doesn't really matter how secure it is.
Many IoT devices (or Windows when the LAN network location is set to “Private”) expose a wider surface area to local network addresses. Having a competent firewall on your residential router is still useful, especially for those that have no idea how to configure their endpoints securely.
Comparing a residential router to a network operator’s router is spurious: those routers don’t perform any sort of filtering for the public internet traffic flowing through them.