Most people only care about the Dow. It is the only American index that most people pay attention to. In fact, most Americans pay attention only to it (no foreign markets and not to other American markets) - and to gasoline (oil) prices. That is the only thing they react to.
That does not mean the S&P 500 and the Nasdaq aren't important - they are, and I report on them too - but, frankly, most people in America, at least for all practical purposes, don't even know that the S&P 500 exists, and they pay very little attention to the Nasdaq, as well.
For that matter, the S&P 500 is often, even frequently, in sync with the Dow. And if it isn't, it is usually not far off.