Says who? I drive my 5v relay’s just fine from the power supply… then the GPIO signal from the ESP is fine 
Similar project of mine "SONOFF Clone" - Mini-ESP8266 Power AC Relay Controller
Says who? I drive my 5v relay’s just fine from the power supply… then the GPIO signal from the ESP is fine
Similar project of mine "SONOFF Clone" - Mini-ESP8266 Power AC Relay Controller