You could also say all the speakers at this conference are too young, too old, too corporate, too hipster, too southern, too Yankee, ....

You can't really create diversity directly (people feel comfortable around those like themselves), instead it happens organically because people turn out to be naturally different, BUT you can definitely act against it through bias based on gender, ethnicity, age, looks...

The goal is to let diversity thrive through environments and hiring practices that are free of unnecessary bias, but old habits take a long time to break.