Yes correct - my misunderstanding.
But putting pots in series with a load that may cause a relatively large current is that you have to take into account the dissipation of the resistance in circuit at the time. A pots dissipation is rated for the whole pot and so the dissipation in the part limiting the current may be quite high and well out of specification and in some cases will cause the pot to fail. Remember dissipation goes up as the square of the current so a linear drop in resistance will cause the dissipation to rise faster and faster.
The other factor you may want to take into account is how you want the brightness to vary - a linear increase in brightness with the pot rotation. The power dissipated in the load will not be linear with a simple series resistor but power controlled by changing the mark to space ratio (hence duty cycle) in a PWM controller (very efficient and linear) will cause an almost linear change in brightness with pot rotation.
Addition:
If you would like to change brightness using a series resistor it would be preferable to use a multi-position rotary switch (say single pole 5 position) and switch in individual resistors to get 5 brightness levels for example.
Jerry
