An Adafruit article showing people how to wire up an RGB LED to an Arduino UNO has the warning shown below on its page.
For longer strips requiring more than 1 Amp, wire the power directly to the strip, then run power and ground wires back to the Arduino.
I understand that you can connect ground wires together, however, it's advising us to run power wires back to the Arduino. I don't know what this would mean as I don't think a +12 Volt line will do the Arduino any good as it runs at 5 volts. Is this a typo on their end or is there something I'm missing here?