I think "centrist" and "moderates" are pretty bad terms. They are usually used to capture anyone that doesn't fall cleanly into the two main parties. Which honestly, is a very diverse group. One such issue (of many) with this is that many anti-authoritarian people fall into this camp. It does make sense that these people get burned out as there has been no representation for them in decades and their major concerns have only grown ever stronger and seem nigh impossible now. The right did capture some of these people (re Tea Party) until they typically find out they are hoodwinked. Now the left is capturing some of these people because Trump was the personification of authority. Still, I don't think these people feel represented and I don't think you should dismiss them so easily.