After all, consider the alternative. Complicated and confusing interfaces force users to find solutions to problems that shouldn’t be there in the first place. A user who feels confused by the options, the interface, the navigation and so on will likely feel overwhelmed in their thinking process. Even momentary pauses are enough to rip users back into the reality that they’re sitting in front of their computer.

This excessive thinking is called cognitive overload, and here we’ll explain how you can avoid it. First, we need to explain what exactly in our brains is at risk of being overloaded.

Many design variables have the potential to tax the user’s brain, and many more variables in the user’s external life and environment are beyond your control. A user could be worried about a work presentation the next day, or there could be loud construction right outside their window — these things will drain their working memory, regardless of how simple your website design is.

https://www.smashingmagazine.com/2016/09/reducing-cognitive-overload-for-a-better-user-experience/