People were already generating html back then and the output of those programs was "simpler" in the sense the html would just have tons of complicated inline fo

People were already generating html back then and the output of those programs was "simpler" in the sense the html would just have tons of complicated inline formatting attributes on each element (that was completely opaque and impossible to edit by hand), so that's what it looks like when you don't need the output to be human editable. The point of css was to fix this.