Can you keep the edges of vector elements smooth past 100% zoom in After Effects?
Don’t zoom in on your display to do this. 
Adjust the scale on the layer to zoom in further. 
If the sun icon is enabled on the layer, you will get sharp edges as you scale up. Then position your anchors accordingly and scale back down if necessary. 

Zooming in on the display will only show you pixel level accuracy for the resolution of your comp, so if you comp is HD you will never see higher resolution than 1920x1080, as that is the resolution at which the comp will be rendered.