Superglue only has strength in shear, i.e when the force applied to the joint is parallel to the surfaces being attached. It is an adhesive, and adhesives generally have pretty poor performance with any kind of load.
Superglue has very little no almost no strength in tension. An example would be if the halves of an aircraft fuselage are adhered together with superglue, the wings are attached and the wings are then flexed in any way, the fuselage joint will crack immediately.
If you use it to join together parts that have any kind of coating, are not prepped or are dirty, the adhesion is greatly reduced, only having the value of what ever coating or other substance has with the bare plastic.
As noted above, Tamiya Extra Thin, Acetone, Testors and other solvent glues form a bond by melting and fusing the plastic surfaces.
I use solvent glues on plastic for anything structural, such as ship hull halves, wings to fuselage, or components of a car body. Anything that can be glued first and painted later.
Because the adhesion of superglue is poor, it really works best for me with smaller prepainted parts being attached to larder sections of the model.
Tamiya Extra Thin and other solvents cannot be used to bond anything together except plastic, so superglue is required for resin kits, an alternate there being epoxy.
Morrison's Second Law: There's never enough time to do it right, but somehow there's always enough time to do it over.