A chord is comprised of at least 3 notes. Octaves of these notes don’t count as separate notes. So the maximum number of notes a chord can have is twelve. This is all the spacings in the octave. Since we like to play in a normal scale, chords usually only go up to the seven notes a scale is comprised of.
So called power chords are not chords because they are comprised of only two notes. The third note is an octave of the root note.
The major and minor chords are comprised of the minimum three notes. I define a fat chord as having 4 or more notes played at the same time.
I love fat chords. Some of my favourite bands like Yes and Led Zeppelin used fat chords all the time. In the late 70s backlash to these bands, punk rock and later styles of rock guitars rarely used fat chords. Since I enjoy fat chords I want the backlash to end once and for all. So I will try to embarrass punk rock and other musical styles that try to demand simplicity.
I’ve played guitar for decades and I’ve heard people, even those that like simplicity, say it sounds more like a real song when you sing notes that are not in the chord you are playing. I whole heartedly agree. If simplicity seeking people are playing only major and minor chords while singing more unique notes, then the whole act is hitting those fat chords.
So what of punk rock and heavy metal when they are using exclusively power chords? Well if there is unique note harmony going along with the unique note lead singing then they are also using fat chords.
If there is no harmony and just power chords, the bassist has to be watched carefully. If they hit unique notes then there is also a fat chord situation.
If the bassist is reigned in, it should be noted that drums can kind of be tuned and they can also add to the fat chord situation.
In my opinion, most guitarists eschewing the use of fat chords aren’t usually espousing a philosophical position, but are more likely showing their ignorance because they never learned fat chords.
Most music contains fat chords when you look at the act as a whole. My love of fat chords isn’t as weird as some have made themselves believe.