Triads, or three note chords, are incredibly fun to play and sound great. You just learned how to play a C major triad and find yourself playing it over and over again, “C-E-G” is literally all you can think about! But after a certain amount of time, they can go from exciting to boring. They aren’t frequently used because many artists and musicians tend to find them boring after a while.
Sometimes practicing the piano can get kind of boring, repetitive or hard. I talk to a lot of people learning piano and they always tell me that they “dread practice” but “love playing.” It’s hard to improve your piano playing skills if you enjoy playing, but you can’t get a lot out of your practice routine.