Why do mature AWS shops avoid IAM users for workloads? Where do instance profiles and IRSA fit in?

Roles versus users looks like syntax trivia and is actually a secrets-management position. The follow-ups about instance profiles and IRSA separate practitioners from tutorial graduates.

Grounded in researched DevOps, SRE and platform engineering interview loops, written to a senior-engineer editorial bar, and never padded to hit a word count.