Systems tend to not have particularly strong guardrails against pathological access patterns which aren't trying to use 100% but a large multiple of that or are

Systems tend to not have particularly strong guardrails against pathological access patterns which aren't trying to use 100% but a large multiple of that or are abusing some subsystem or another. The application is almost always also unresponsive. Putting up those guardrails temporarily hides big problems more often than it avoids needing to have them solved.