Extremely good points. But the thing is, self-discipline is not the same as power. When I say power, I mean as in raw Force power. It just takes more self-control to stay Light Side. But am not talking about self-control, but outer, physical strength.
But joining Dark Side to get power "quicker" as in trimming a couple years off training? Doesn't make sense. There's more to the Dark Side ideology for that. Jedi get power fast as well, since they can fight as Padawans even as a small child.
You saying physical strength.
Some people will always have more physical strength than someone else.
How does that relay to force powers? Do you truly believe that is someone has more physical strength they are more powerful? The force powers do not rely on physical strength.
Each force user could have different force abilities. Such as Bastilla Shan . She had a rare ability battle meditation.
If you are looking at force powers based on physical strength you may want to look at a definition of force powers:
Force powers were the manifestations of a Jedi, Sith, or other Force-adept's connection with the Force. These powers were supernatural abilities not described by scientists. The powers were usually taught by Force-using organizations, but there were examples of individual, self-improving methods of learning to use the Force. There were many kinds of Force powers, but not all were available to a single person, since some of them required a deep connection with one side of the Force and others were secret or very rare. Also, as a side note, it should be taken into account that the Force is not "magic," nor does it have specific "spells" or "powers," and they are far more interrelated than the list might suggest.