If you play in a group with say a guitar and a bass guitar then any "inversion" the guitarist plays is just a voicing. the real inversion is decided by the bass player.
Equally the guitarist can play simpler(or just other) chords where required. e.g if the guitarist plays Em and the bass plays a C# it is a C#m7. Assuming there are other part to cover the gaps you can often get away (or even improve) your voicings by leaving out notes. The power chord is just one example of this.
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