Three distinct SaaS categories are simultaneously reporting the same structural problem: AI reducing the number of human seats needed. Atlassian (project management) reported its first-ever enterprise seat count decline and cut 1,600 jobs; MongoDB (developer database) fell 42% as vibe coding reduces developer count per project; ServiceNow (ITSM) dropped nearly 50% from peak on fears that AI agents eliminate the support tickets that drive seat purchases. The pattern: AI doesn't just compete with SaaS products — it shrinks the workforce that uses them. If one AI agent replaces 10 knowledge workers, that's 10 fewer seats across every SaaS tool those workers used.