The advice I took from Levi's story is: consider the possibility that things you take for granted as necessary actually aren't. They could be mistakes, or artifacts of limitations that have since disappeared.
(It's particularly useful for startups to notice the latter, incidentally. A lot of existing businesses turn out to be artifacts of limitations that have since disappeared. E.g. hotels are to some extent a hack to get around the fact that it used to be impossible to search all the available space in the city you wanted to visit. If you built a whole building full of bedrooms, you could afford to pay to advertise it and to pay someone to work full time taking reservations.)
(It's particularly useful for startups to notice the latter, incidentally. A lot of existing businesses turn out to be artifacts of limitations that have since disappeared. E.g. hotels are to some extent a hack to get around the fact that it used to be impossible to search all the available space in the city you wanted to visit. If you built a whole building full of bedrooms, you could afford to pay to advertise it and to pay someone to work full time taking reservations.)