Novel and ff ideas for authors

I wonder why isekai stories where they got transported or summoned in another world they always end up too overpowered so i started to think why don't you make an mc where he got summoned in another world as a weakling and doesn't have a system. And people who support the mc and of course the power system of the world has to be weak of course cause its impossible for him to survive if monsters and demons roaming around that can destroy a mountain or a city with a single attack, so you must make the world not too overpowered and just give him something an average person would have.