In my experience running large sites, dedicated hardware is not only cheaper but orders of magnitude faster because you can finely-tune the hardware to very, very specific use cases, and you can have a fully private, highly optimized network with very small cable runs to effectively eliminate network latency issues.
Most of my current job involves solving problems that are caused by cloud limitations.
And if you need throughput, 40gigE / 56gigE is not that hard expensive with your own hardware. You end up with like 4x to 10x servers to handle the same load.
Most of my current job involves solving problems that are caused by cloud limitations.