Absolutely correct. One way to think about it is to imagine what would happen if you were to saw through the joist at a particular point. If the two cut ends would move apart laterally then there's a shear force present. For any particular loading of a beam there's a simple differential/integral relationship between the shear stress and the bending moment - the bending moment is the integral of the shear stress with respect to distance along the beam. (So, for a simply supported beam with a UDL applied, the shear curve is a straight line going through zero in the middle of the span and peaking at the ends and the bending moment curve is a parabola, highest in the middle and zero at the ends.)
Having said all that I think there's usually a fairly large factor of safety wrt shear strength in house joists, as the size required tends to be determined by deflection considerations rather than strength alone. So drilling small-ish holes slightly nearer to the ends than you're supposed to is unlikely to lead to any great disaster. OTOH notching near the middle of the span is a definite no-no.
[Disclaimer - IANAStructuralEngineer; no responsibility assumed for anything at all; seek proper professional advice; the value of your investment can go down as well as down.]