How did control of the Hejaz benefit the Fatimid caliphs?

Control of the Hejaz, which included the holy cities of Mecca and Medina, provided the Fatimid caliphs with significant advantages:

• Religious Prestige: Holding the two holiest cities in Islam conferred immense religious authority, reinforcing the caliph’s claim to be the legitimate leader of all Muslims and the spiritual head of the Ismāʿīlī community.12
• Economic and Strategic Value: Control of the region allowed the Fatimids to exploit the annual pilgrimage for political and financial gain. Furthermore, it helped them monitor the western Arabian coast and supported their broader economic policy of revitalizing Red Sea trade routes between India and the Mediterranean, which undermined the rival Abbasid trade routes through the Persian Gulf.12