And to add to Erik’s answer…
We say ‘no’ because it introduces more problems than benefits and in some cases it isn’t possible. Of course most of us don’t see the point of doing it. Typically, any increase in speed diminishes battery life and most people here purposely bought the TR for the long battery life.
Also, it’s my opinion that overclocking is overrated. For the most part, current available CPUs are so far ahead of most general software (except for some games, scientific programs, and some multimedia apps) and run them more than fine.