I know that's what many people, especially elder one, say but this is still a hill I will die on :) They are mostly used to go in mostly flat roads, like some slow-speed motorcycle that needs some low effort. The ones using them outside paved road, using them as multipliers, are the ones that already did mountain biking when they were younger and they want to continue doing it at a higher level their age would permit without (which it's perfectly fine!).