Man gets isekai'd, becomes amazing by pointing out the fucking obvious to "experts" who should know better.
pretty bad.
It’s obvious to him and us, but to them it was something you didn’t question or had the knowledge to understand it to the point of practical use. If it was so obvious to geniuses back then why don’t we have Tesla cars or lightbulbs or the springs in carriages in medieval ages.
The knowledge of impurities in metal in that world are family and disciple secrets to avoid others from learning and using their methods that would take away jobs from them and others gaining an edge by learning their work secrets.
We also don’t know what age they are at or if it’s structured similar to that age.
Notice that these people are considered geniuses because they were given hints that they would not have known or thought of because the concept or knowledge was not something they knew or could know prior too unless it was something public or had access to.
Yes some things are so simple but now a days I even look at older eras and think “this is super simple how did no one even remotely think of this?”