It might be more correct to say that Certificate Pinning made it so you can't inspect your own traffic - for sites with TLS but without certificate pinning, you can just as easily create your own root certificate and force the browser and OS to trust the cert by installing it at the OS level. This is (part of, atleast) how tools like Fiddler and Charles Proxy allow you to inspect HTTPS traffic, the other part being a mitm proxy that replaces the server's actual cert with one the mitm proxy generates [0]
[0]: https://www.charlesproxy.com/documentation/proxying/ssl-prox...