How in the fuck are people actually defending signal for this, and with stupid arguments such as windows is compromised out of the box?

You. Don't. Store. Secrets. In. Plaintext.

There is no circumstance where an app should store its secrets in plaintext, and there is no secret which should be stored in plaintext. Especially since this is not some random dudes random project, but a messenger claiming to be secure.

Edit: "If you got malware then this is a problem anyway and not only for signal" - no, because if secure means to store secrets are used, than they are encrypted or not easily accessible to the malware, and require way more resources to obtain. In this case, someone would only need to start a process on your machine. No further exploits, no malicious signatures, no privilege escalations.

"you need device access to exploit this" - There is no exploiting, just reading a file.