With Power systems you just add boards with X sockets to a rack and plug infiniband you are done, do this as many times as you want practically without performance costs, Intel/AMD systems can't grow that big without custom desgined hardware and clustering techniques that have a bigger performance leak penalty.
this are the scenarios where IBM Power Systems are actually cheaper than Intel/AMD in the long run[same apply to sparc], the point is they are designed for different scenarios.
just ask the experts how much will cost you to put 2 thousand Xeon CPU to work together and then ask IBM how much it costs for the equivalent in Power and you will see what i mean.
so the norm here is if you need to run many massive SAP[to stay topic] semi isolated system that each could handle million of transaction per hour and eat RAM like a turbo V8 an require centralized access to a massive terabytes long sets of Oracle/BD2 instances as fast as the technology can allow with rock solid stability and world class personalized support, Oracle Sparc/IBM systems are a no brainer
if you have an SAP system single instance with a gigabytes long Oracle/Db2 database that process millions of transaction per day/week and would never map more than 512GB of ram, IBM/Sparc are waaaayyy to overkill[like killing a fly with a nuke] so here intel/AMD is a no brainer