Reading a file and code execution (which is required for reading another processes memory) are two different levels of vulnerabilities. Essentially if you have

Reading a file and code execution (which is required for reading another processes memory) are two different levels of vulnerabilities. Essentially if you have a piece a software with a bug that allows someone to remotely read files from you system, your browser stored passwords are compromised while your passwords stored encrypted are safe-ish depending on how good your passphrase is. Of course if you have malware that can run arbitrary code on your system you are hosed either way.