Something I don't understand about this argument, which has been made before, is you can tie JavaScript to a specific hash with SRI. So you release the cryptographic code in public where it can be audited and then what runs in the browser verifies that was what loaded.

The host could inject malicious JavaScript from the host or change libraries but I feel like this is an avoidable problem because it can be audited much more easily than expecting users to audit JavaScript every time. People could even build known, trusted, web frontends. So I think there are mitigations if not ways to assure the browser is running trusted code.