They can - but not for very long

2 main reasons
3d planes have large control surfaces that have a tendency to flutter at high speeds. this usually results in mid air destruction of the airframe and is near impossible to stop.

The large control surfaces are usually way too effective so at high speeds, the slightest movement of the surface results in a change of attitude of the plane.

Also - the airfoil sections etc are not designed for speed and they tend to have a lot of drag. If you were to try and power one to go fast - it would take a HUGE motor to get a good speed.