The silk radical 纟 marks continuation — threads tied to threads. 绍 originally meant to carry on a lineage, connecting one generation's thread to the next. 介绍 pairs 'stand between' with 'tie the threads': introduction as knot-tying between people.
绍兴 Shaoxing — 'continuing the prosperity' — is the city of yellow rice wine and Lu Xun's hometown. The wine 绍兴酒 ages for decades, buried in daughters' birth years and opened at their weddings: continuity in a jar.
Summon 召 a silk thread 纟 to TIE two people together — an introduction.
In job-hunting Chinese, 内部介绍 'internal introduction' — the referral — is universally acknowledged as worth more than any resume.