There are many words to describe an information-heavy design. Some may call it cluttered, complicated, busy, or overwhelming. As a result, the designer assumes they need to reduce the amount of information displayed on the screen. However, showing too much information is not the real issue.
Removing some information could help, but the fundamental issue is that too many elements are competing for the user's attention. This visual competition makes a design look cluttered, complicated, busy, or overwhelming.
Visual competition exists when you fail to direct the user's attention toward specific elements. You should never treat everything on the screen equally, or you'll create a "busy" effect.
