There are trade-offs between the so-called “full spectrum” phosphor-coated blue LEDs and utilizing multiple different colors or “bands” in LED grow lights.
“White” or “broad-spectrum” LEDs can provide for plants’ minimal needs for growth, and if they are based on UV LEDs (which almost none are) they can even provide all the colors of light plants need to grow ideally. However, they do not produce all of these colors in the ideal ratio for plants. Most “full spectrum” LEDs produce predominantly yellow light, which is absorbed by plants but is not directly usable. The yellow light heats up leaves more than is necessary for ideal plant growth in indoor gardens, requiring additional cooling to keep the plants from overheating.
By utilizing multiple different kinds of specific-color (“bands” of) LEDs, LED grow lights can perfect their spectrum and provide plants with the colors of light required for photosynthesis / growth as well as just enough of the other colors to grow perfect plants.
In general, more bands of LEDs will make a more-efficient LED grow light, but there are always exceptions. Including unnecessary colors purely to increase the number of bands may make for better marketing for an LED light, but it won’t grow plants better.