Not all the pins in the 40 pin gpio header are gpio pins. its just quicker/easier to say gpio rather than gpio and power rail/sources.
its a bit of a confusing name in that respect. the gpio pins are pins that are connected to the pi for either input or output, the 5v, 3.3v and ground pins are not gpio pins but pins that are connected to the respective power rails used by the board.
the fact that you can power some low power 3.3v components by switching a gpio pin to output and high may have helped in the confusion.
but only the specified gpio pins are gpio;) and the gnd 5v 3.3v pins are just that power pins..
with the blinkt https://learn.pimoroni.com/tutorial/tan ... ith-blinkt
it plugs into the whole header, im sure if you delve into its documentation it will tell you if its using /connected to the 5v supply and if it is it will be for the power to drive the leds, the control circuitry connected to the spi bus will be limited to the 3,3v level the pi uses for gpio pins..
when using the 5v pin on your pi you MUST pay attention to protect your gpio pins from that voltage. check out optoisolators/optocouplers and logic level shifters