[garethmcc]

Not to mention that that same infrastructure you say is in abundance is usually pretty heavily utilised already so there isn't just spare capacity lying around. Procuring new hardware can take months and if there is no rack space you are looking at more months to get that deployed.

The people that need to plan, coordinate and install all of this are also pretty heavily overworked at the moment because, believe it or not, there is a very large shortage of skilled sys admins in the world.

Using the cloud doesn't solve those problems, but it does help reduce their impact.