There's more gray area than that obviously. The Metal Zone is a great example. It's a distortion pedal, but it sounds pretty good as a preamp thanks to its EQ flexibility and that can of bees sound actually works out okay into a power amp. I think it's fair to say there is some misleading marketing to it, but I feel like there are some pedals that can justify being called a preamp. Where you draw that line is arbitrary because realistically just about any distortion pedal can be made to work as a preamp. I'm just speaking from my experience in trying out various distortion/preamp pedals into a solid state power amp and what has worked.