This is true, but with modern applications, it tends to be more economical to scale out vs up.
If you're running a big implementation of software that scales up or has licensing rules that make scale-out expensive (ie. Oracle), Power is a no-brainer. Problem is that generally speaking, the industry had gone a different path.
As always this is a "right tool for the job" discussion. There's no silver bullet. But the fact that price rises faster than performance the closer you are to peak performance doesn't say anything about the value of the product. The problem is usually when you can no longer scale out. You'll see the same with storage, GPU, RAM, etc.
If you're running a big implementation of software that scales up or has licensing rules that make scale-out expensive (ie. Oracle), Power is a no-brainer. Problem is that generally speaking, the industry had gone a different path.