Why it matters
You can't prevent every failure. You can recover fast.
There's a seductive but impossible goal in engineering: never break anything. No team that ships at any reasonable pace achieves it, and chasing it leads to fear, batching, and slow deployment. The mature alternative is to accept that failures will happen and get extraordinarily good at recovering from them. MTTR measures exactly that capability — and it's the metric that lets a team ship boldly, because if a deploy goes wrong and you can revert it in minutes, the cost of failure is small and the risk of shipping is low.
This is also where MTTR protects the rest of the business. A failure that takes minutes to resolve barely touches your uptime budget; one that takes hours can blow it. The same failure, with a fast MTTR, is a blip customers barely register, and with a slow MTTR is an outage that spends real trust. Recovery speed is the difference between an incident and a crisis — and it's the safety net under your change failure rate, since the failures that do slip through cost far less when you bounce back quickly.