Note that what jefftk calls "open chords" are more commonly called "power chords" (or "indeterminate" or "no3" or "5" chords). This is a distinct concept from the open/"zombie" chords that that youtube video is about. (But if you did use only power chords when covering songs, they would also usually sound quite dull!)
But it's not just about open chords. If you strip down a Bm7b5 to a Bm and play the Bm on the second fret it still has half of the character of the Bm7b5 chord.
Only recently did I start gaining the patience to learn every suggested chord and it makes a tremendous difference.
That said, I prefer piano for accompanying because the piano's tone is somehow more forgiving with basic chords than guitar is.
One other thing that makes it harder on guitar is that the chords that are easy to play are often various inversions, so your "A" chord might actually be a first or second inversion. I'm still just learning movable shapes on the guitar, and getting the fingerings right is tricky as things grow and shrink moving up and down the fretboard, something that also isn't a problem with keyboards.