You may have heard things like, “explain it in one sentence”, or “explain it to me like I’m five.” People ask these questions to find out the concept behind an application.
An application is then composed of a number of modules, each of which can be described with one sentence. Sentences all the way down.
Good conceptual descriptions can help developers come up with useful abstractions and work within boundaries. Abstractions inspire algorithms and structures in the code.
Clear concepts make it much easier to have good documentation, navigate through a project, name things, and decide where things go.
The application takes on more and more features. At some point the structures, abstractions, algorithms, and maybe even the concepts will no longer fit.
At that point you will have to refactor, move around code and come up with new ways to describe the new situation. At a higher level you may re-architect or even pivot if it changes the business.
The danger zone is when you don’t do these things.
In business terms that means you end up with a flower shop that also employs a pediatric nurse. Confused customers are bad for business.
When you disregard concepts and abstractions in code you break the principle of least surprise. Eventually that leads to hard to memorize complexity, which leads to operational errors and bugs.