Using currently proposed models, this might be true. The facilities and reaction apparatus don't scale well, so power generation plants would have to be massive

Using currently proposed models, this might be true. The facilities and reaction apparatus don't scale well, so power generation plants would have to be massive, and using tempermental, super high precision, enormously complex equipment means huge infrastructure, operation, and maintenance costs. As materials, theory, and science in general improve, designs will get better, and someone will crack the puzzle of scaling, but that's 10 to 30 years out, as always. We might see a viable fusion engine for spacecraft before practical fusion power on earth.