If your product is profitable then being able to scale the server side by buy bigger/more servers (aka throwing money at the problem) can be a great approach. It means no new code write, and more importantly, no new code to test. There can be much bigger gains by updating your software but the costs are much higher and the turn around time is generally longer (for major updates).
This is not a valid approach on the client side though as you don't control the hardware.
This is not a valid approach on the client side though as you don't control the hardware.