Experiment: Red Light vs Blue Light -How Spectrums Affect Plant Growth- LED vs CFL

Blue light vs Traffic signal. Which is much better for vegetative development??? Intuitively, the answer might appear apparent: Blue light is for vege! That fundamental mantra has been plastered all over the internet. But if the issue was so basic, then why is it that so many LED grow lights are sold utilizing such a large ratio of red to blue? Why don't we see many pure blue "vege" lights? Wouldn't nurseries…