It may not be the absolute goal on itself, but in practical, the focus is on the shield as it is encountered before anything else, so it part of a tactic.Exactly. Nobody deliberately aimed at the shield.
The soft tip/shaft concept is in this context still an important concept and was introduced with a good reason.
Romans deliberately threw at shields to penetrate them, according this roman text.
"As to the missile weapons of the infantry, they were javelins headed with a triangular sharp iron, eleven inches [279 mm] or a foot long, and were called piles. When once fixed in the shield it was impossible to draw them out, and when thrown with force and skill, they penetrated the cuirass without difficulty".
"They had likewise two other javelins, the largest of which was composed of a staff five feet and a half long and a triangular head of iron nine inches [230 mm] long. This was formerly called the pilum, but now it is known by the name of spiculum. The soldiers were particularly exercised in the use of this weapon, because when thrown with force and skill it often penetrated the shields of the foot and the cuirasses of the horse".