The entire concept of “Web design” is a misnomer. Individual project teams are not designing the Web any more than individual ants are designing an anthill. Site designers build components of a whole, especially now that users are viewing the entirety of the Web as a single, integrated resource.
Unfortunately, much of the Web is like an anthill built by ants on LSD: many sites don’t fit into the big picture, and are too difficult to use because they deviate from expected norms.
Several design elements are common enough that users expect them to work in a certain way. Here’s my definition of three different standardization levels:
Standard: 80% or more of websites use the same design approach. Users strongly expect standard elements to work a certain way when they visit a new site because that’s how things always work.
Convention: 50-79% of websites use the same design approach. With a convention, users expect elements to work a certain way when they visit a new site because that’s how things usually work.
Confusion: with these elements, no single design approach dominates, and even the most popular approach is used by at most 49% of websites. For such design elements, users don’t know what to expect when they visit a new site.