I have memorized all of my social media passwords, some of them are over 50+ digits long. Sounds insane, right? I know. But I have read/used them so many times, they are basically on the tip of my tongue.
You will always have a way to recover your social media accounts and many other accounts. There are secondary emails and ways to verify who you are to regain access. The Bitcoin protocol doesn't have a central entity who will give you the keys again if you lost them and help you with your lost seed. That is generated locally and that's where it's supposed to be backed up as well. Backed up in a way so that there isn't a single point of failure. The memory alone is a single point of failure. It's more of a last resort option, imo..
But you do you - surely, memory is the thing that can fail us, but it's also what is always with us
