There is a lot of debate about whether "memory" optimizers do anything -- I won't get into those.
Process Tamer and similar apps are doing something different.
Process Tamer changes the priority of apps so that some apps get more cpu cycles from the computer than others every second.
It's a very specific action which serves to make your computer more responsive to your input, by slowing down programs which would otherwise dominate the cpu, OR by doing the opposite -- giving certain programs more of the cpu so that they perform faster, but at the expense of slowing down other programs and the operating system user interface.
This is not magic and it's not a hoax, it's a real feature that can be useful in certain cases.
(The prevalence of superfast multi-core cpus makes tools like Process Tamer less critical than they are on slower single core cpus, because with multiple cores it's not often that your computer will be unresponsive due to a single program hogging the cpu).