You don't need to read every word of everything, but some things are worth it. Do you sign contracts without reading them too since it's a "terrible use of" your time?
Yes - I am saying in this particular car example, the benefit derived reading the entire manual before purchasing/driving a car is not worth the cost unless your time is worth very little. As others have pointed out, no one is flipping through the manual to check whether the brake pedal actually applies the brakes
But it is a good engineering decision to thoroughly read the docs before jumping into a new datastore like Mongo, I agree. Learning there are things like gigantic global locks and unsafe writes are normally enough to make you say, "hey, I probably shouldn't use this to store production data I actually care about"