Even Keepass's "encrypt in memory" option leaves that encryption key in memory, so it can auto-type or copy passphrases into form fields. It's an extra step, but not unbreakable.
And even then the passphrase is put into form fields in plaintext, so there's *got* to be some sort of attack to grab those. They must be in memory decrypted at some point.
It always comes back round to "you can't have your cake and eat it".
It always comes back round to "you can't have your cake and eat it".