There are many voicings out there.  Eventually, we want to be fluent in many of them, but we need to start somewhere.  Maybe you're looking at rootless voicings.  Maybe your teacher started you on the 3 and 7 guide tones.  We had to pick one way to start off, so I picked this one - the simplest.  The 3 and 7 tones.  But did you know that learning these foundational chords can later help you with scaffolding your knowledge for other voicings?  That is because the 3rd and 7th chords have very special properties, and most other chords are built on them.  So you're really learning the basis for future chords, as you learn this particular voicing.