It's not that the manufacturers would decline smaller orders, it's more that they stop making metal halides altogether because the big orders that were sustaining production in the past are dwindling down to a trickle.
In the past the lights at gas stations for example would be 250 or 400W metal halides. These days all you see there are LEDs. Same with industrial and street lights. For the majority of the manufacturer's customers the light spectrum is of secondary consideration. What they care most about is energy efficiency and maintenance cost. And in that department LEDs win big time. Almost all new installations these days are LED.
The days of metal halides are numbered.
LEDs Prove More Efficient Than Metal Halide Lamps for Factory Lighting