I believe we must have seen or heard about fire outbreaks, where buildings are completely erased by fire. Imagine if the owner or occupant of such a building has some Bitcoin assets, and has his/her phone, tablet, laptop and the seed phrase piece of paper in the building and everything was lost to fire. Now, this brings me to the question... Can seed phrase be memorized? It's advisable to memorize seed phrase?
Memorizing is not a perfect way to store seed phrases, what if you accidentally forget one of them? You will no longer have a chance to get your assets back. That is not a viable solution.
There are many ways to store seed phrases, but none of them are absolutely safe because, as you say, incidents like fire, flood, natural disaster... such things are unpredictable. The best we can do is make different copies and store them in other places, this can help you avoid unexpected losses.