Because they are expensive, they have very little battery life, they break easily (expensive again), they may get stolen (I can leave my 10€ phone anywhere, I w

Because they are expensive, they have very little battery life, they break easily (expensive again), they may get stolen (I can leave my 10€ phone anywhere, I wouldn't do that with my 600€ one), they do everything computers do, only at a tiny impractical screen, there is a notion of more radiation from smartphones, they make it much more attractive to waste time, they are much slower to boot up = people don't want their smartphones do be always on/standby, they are more unreliable in terms of glitches / connectivity issues / bugs.