Actually that's an inaccurate but correct statement. A more correct statement would be that they are part of the secret with the total secret being that all the elements of today's indoor grows enable us to produce a superior product indoors because we can mimic close to ideal conditions and filter out alot of the traditional hazards. It wasn't all that long ago that indoor growing was not viable or affordable for the average person. Nowadays it's all turned around even the right fluoros can produce a decent yield. The thing to keep in mind though is it's not just the bulb. I mean you can make a fair argument that a 1000W HPS is only practical due to the invention of the cool tube and therefore the cool tube is the true secret.
It's also misleading to say a light makes a plant grow faster. The length of time a plant takes to flower is pre-determined genetically in the seed. Having a brighter light isn't going to change that. The sun however follows a certain schedule due to earth's orbits and there's nothing that can be done about that, whereas in a growroom there's all sorts of ways to manipulate the plants and the light schedules. For example, it's common knowledge that clones finish in flower slightly faster because they are already fully mature the moment you start 12/12. So you can go with a shortened veg or even no veg in some cases and still end up with a decent harvest. In essence the bottomline is that the only way an indoor grow out performs the sun is because indoors you can complete as many as 6 crops a year whereas outdoors under the sun you can really only get one crop in, at least in most places.
