The problem with shot alignment by way of contact points or fractions is you're trying to exactly link two minute parts on both the OB and CB which are located and viewed at the fat areas of both balls with about 2mm between each contact point or fraction. A visual mistake on either ball or both results in a missed shot. It's like trying to thread a needle which can be difficult to do. It has to be exact.
This is just a description of the moment of contact. There is no problem with contact aiming. It's geometry. It shows you exactly what the shot is. The equipment has all the functions of the shot built in. The balls will in fact sit there until you place your cue on the shot and set it in motion. There is no curvature or dimensional shifting involved in this process. IOW the balls don't change shape or size or oscillate. You just shoot the shot. It does require that you have developed the appropriate skill set; something on the order of a good well rehearsed stroke.
Fractional aiming is another estimation technique and not a concern here.