Only due to the fact the ballasts manufacturers do not make other wattage ranges, nothing at all to do with any limitation from the ProfiLux
in Europe all wattages are available, it is just in the North American market Sylvania being the only dimmable ballast maunfacturer with a 1-10V interface have only thus far launched 54 watt to the market. I have no idea why when they have the full range for 220v.
So a i say, not limited by profilux, but limited by what ballasts are available.