[spion]

Because it makes points of potential interleaving obvious. Without await, you have no idea whether the call will block or not, and whether whatever shared state you accessed before the call will remain the same after.

With await, you know. If there is no await, the call will not block, and more importantly, shared state cannot be modified from outside of that block of code. If there is await, there are no guarantees and you need to take the necessary precautions.