The trend line does not tell you what will actually happen at scale, even if you think you're perfectly prepared for the next 10% or 20% growth. As Mike Tyson put it, "everyone has a plan until they get punched in the face".
The problem is there are a class of problems that only appear after you go over the tip of what your system can handle, which are very difficult to predict or model.
Doesn't Azure have such options so that engineers can predict to scale better? Seems like engineers are not ready for this per postmortem