If you're told not to do a piercing side kick because a thrusting side kick is "correct", then you are more likely to think there's something wrong with the piercing side kick.
If I teach one way, and another instructor with a different background and set of experiences teaches a different way, then we could:
- Explain the pros and cons of each version of the technique.
- Describe the situations you would use one version over another.
- Throw the other instructor under the bus as being inferior.
Two of those allow the students to
gain understanding of the technique. The third causes the students to
lose trust in the material being taught.