It does, because vectors don’t actually don’t stay vectors within AE. Everything is rasterized to the comp resolution, so when you zoom into the comp, things look pixellated.
However, when you click the Continuous Rasterization switch, vectors are continuously rasterized to the comp resolution. With the switch off, the vector is rasterized once, at the original AI document size, but when the switch is on, the vector is rasterized at whatever size to which you scale it up (or down) at every frame of the comp.
But it’s rasterized to the comp size, so it only looks clean when viewing at 100% or less in the comp window. Which is normal, and fine.