Electric guitar...

YY1 said

C, D, and G are the "weird" chords that don't have the same shape as the "Black Sabbath" barre chords, or their open equivalents.

You can also do a hell of a lot of rock and roll with just E and A and barre's.

...and palm muting. Learn palm muting. Must. Quiet the strings you aren't playing.
Instantly makes you sound much better, once you get that down.

Click to expand...

But they are simple I-IV-V chords for beginners to use. Adding the Em for a fourth chord is simple for beginners. Plus G is a relatively common key for vocals.

Key of A requires a certain amount of dexterity on the A most beginners aren't ready for as well as the F#m.

Using the key of E requires a B chord as well as C#m; again a key most beginners aren't ready for.

Patience grasshopper. The Sabbath, power chords and palm muting will come.....