Tell me why I can't use MH/T5 lighting systems designed for hydroponics?

[Whiskey]

Why can't I do this?
It seems that they employ the same manufacturers and just change the bulbs to be more red. Prices for the fixtures are really cheap, integrated 150-250 Watt systems run ~$120-150. Why not just get a more appropriate lamp and use them?

Same for the T5 fixtures, the bulbs aren't great but the fixtures look pretty good.

Please let me know what the thinking is around these products.