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.
Those social media companies stores user data on clouds so they literally have a way to help reset passwords and have access to their accouns. But that's far different from seedphrases where if you mix the words, you loss one or more, then getting access to your funds becomes difficult.
Yea, it's possible to brute force your seed, but the chances of you recovering your keys are very low. Fact is, we don't want to mess with things we don't understand. Upon joining this forum, I've come across several ways to store our keys but just few of them are worth a try. it's better to use methods that have clearly been tested and trusted for years now and store our seed using them...