Standards ensure devices from different vendors work together. Without them, you would be locked into single-vendor solutions.
Interoperability. Your Cisco switch talks to your HP server because both follow Ethernet standards. Any WiFi device connects to any access point because defines how they communicate.
Competition. Standards create markets where vendors compete. Competition drives innovation and lowers prices.
Security. Without PCI-DSS, every merchant would define their own credit card security. Consistent standards prevent chaos.