The reported 5.7% year-over-year increase in system-wide comparable RevPAR for Hilton Worldwide in Q4 is a positive indicator of the company's performance and potential for revenue growth. This metric is crucial for investors as it reflects the company's ability to generate income from its properties, which is a key driver of stock performance in the hospitality sector. Given the significance of RevPAR as a performance metric in the hospitality industry, this positive growth is likely to be viewed favorably by investors, potentially leading to an increase in stock price in the short term.