No, i am not suggesting to create your password like this. you can create something like !Went>P@r!$&be$tmem0ryev_r
Something that you can create that reflect to your experience and easy to remember and hard to crack
And how is it easy to remember? If it's some sort of substitution scheme, like replacing O with 0, then it's easy to crack, if it's truly random (which can only be generated by some rng and not human mind), then it's really hard to memorize and you will forget it unless your repeat it multiple times per day every single day.
Compared to that, mnemonic seeds have guaranteed sufficient entropy and they are easy to remember because our brains are good at remembering natural words in sequences.
I am totally with you by this point. So I do think that passphrases are much easier to memorize for the human brain than some kind of random generate password with a combination of numbers and letters.