You're absolutely right harris.

But...There are still stipulations being overlooked here.

You really can't use the HPS alone for vegetative growth. Simply put, you can but you WILL run into problems and deficiencies. This requires you to have an alternative lighting setup simply for vegetative growth. Which adds to the cost of the setup initially.

So the combined expenses and power usage of an HPS setup are just not feasable for some people.

The T5 setup is much more feasable in my opinion because you can take for instance a 4 Lamp setup, mix your Kelvin and use it for the whole cycle of the plant from germination to harvest without changing anything but the light timing.