Engineering leaders often explain complexity with growth: more customers, more regions, more features, more teams.
Those matter. But complexity comes from something more fundamental.
Complexity is the accumulated interest on yesterday's engineering decisions.
A new message bus solves a problem. It also creates obligations: monitoring, patching, securing, documenting, troubleshooting, upgrading, and explaining why it exists.
Those costs rarely appear in the initial review. They are paid gradually over years.
Code does not wake up one morning and become debt.
Context changes. Assumptions change. Requirements change.
The original decision keeps generating cost under new reality.
Simplicity is not just elegance. It is economics.
Every unnecessary dependency creates recurring operational expense. Every additional service increases cognitive load. Every custom workflow becomes another thing future engineers must understand.
Architecture proposals should include not only initial implementation cost, but annual carrying cost:
Organizations would make different decisions if they priced complexity accurately.
Junior engineers often create capabilities. Senior engineers often remove obligations.
They simplify, delete, collapse abstractions, and retire processes.
They reduce the organization's interest payments.