Having frequencies down that low can eat into your available headroom unnecessarily. Even though you can't hear them down that low, as you say you can feel them. But you can feel enough thump from bass frequencies higher than that without needing those below 20 Hz.You can't hear below 20hz but you can still surely feel it quite a bit. Why cut it when there are people with systems that can reproduce it? Does it hurt things too leave it in?
"-ish" -you should use your earsLike to point out that it's more common practice to roll off vocal frequencies at 125Hz, not 50Hz. Nobody is gonna complain about having 'not enough sub' on vocals, and it clears the way for a good drum and bass low-end that you actually can define by just listening, instead of feeling.
Well spoken, planetnine.On the subject of "cheat-sheets" for EQ-ing, you could try using a spectrum analyser or even a spectrogram on a laptop to help you see where the dominant frequencies are.