Why does it matter what kind of random number generation is used during key generation?
E.g. this answer states
7-8 words selected truly at random make a strong password. My problem's with the "truly" here. My thinking is - whatever key I chose with whatever random number generator, the information isn't available afterwards and an attacker can never know which random number generator I used, so he cannot use that to break the key. On the other hand, I can use "just count up" or a super sophisticated hardware generator and both might come up with "12345678" as a key. Of course, an attacker would start with trying keys like "111111" or "3456789", so he will break "12345678" earlier than, say, "93298762", but "using a good random number generator" or "selecting truly randomly" does not mean I cannot get "12345678" as key.