I don't think this is true -- the index rises in proportion to the stock's price. The stock price of company A would have to rise $26.66~ to incur the same index increase as company B.

It does ignore market cap though. So if company A's market cap was $800M but company B's market cap was $3M, and the shares rise as I explained, they'd still have the same impact on the DJIA. That's why it's flawed.

However, it's a really good indicator of investment performance. Just not necessarily market or economic performance.