How do semi hydroponics enable orchids to grow faster?

If done right yes it does. It does this by giving the plant everything it needs in the excat portions of what it needs exactly when it needs it. The trick is to do it right though. It takes years of growing and lots of research to know the fore mentioned things.

There is also a greater cost involved in purchasing the various neutrients needed and a large time investment spent being there at just the right time to feed your plant.

Hydroponics are really a great thing, but it's an expensive hobby. In most circles it's considered old and out of date but there are die hards out there that still swear by it. It comes down to a personal level of interest and time and capital I would think. I personaly like the ideas of it but im not sure of the practical application outside of the greenhouse for hydroponics.

http://www.orchids-plus-more.com/growing-hydroponic-orchids.html