Why does someone need to know how to change the oil in their car, or how a 4-stroke engine works? The information is readily available if you should ever need it, but what's wrong with paying someone who does know that stuff?

Not having a basic understanding of how internal combustion engines work means not understanding one of the linchpins of our civilization as it is today.

I'm not saying you shouldn't be using third-party services - professional specialization is another linchpin of our civilization. All I'm saying is that people should understand these things, in order to have a chance of comprehending the world they live in.