What is the usefulness of bass guitar in rock and roll?

I want people to understand a few things before they answer my
question.

1. I'm not calling musicians and bands stupid nor do i think they have
been doing it wrong for many years . Obviously they know what they are
doing. I'm just asking why. It's just a WHY question.

2. I have many years of experience with music and listen to a wide
variety, especially rock and roll. Realistically, i could probably
name more rock n roll bands than most people.

3. I am not talking about bass in any genre of music other than rock
and roll, and only bass guitar. I get why they use bass in other
musics like jazz or blues, you can actually hear it and it sounds
good.

So, my points:

What is the point of a bass guitar in rock n roll? You can rarely hear
it (90 percent of the time or more.)

Why do people think bass guitar is so important? To me it seems like
the instruments you can actually hear and do all these amazing thinks
like shred 128th notes or play beautiful licks are more important than
the unheard guy playing the same note 100 times.

People say bass guitar is important because it changes the sound of
everyone else, but no one ever took the time to explain how this
works. How does it work? I don't get it because you can't hear the
bass.

Now, I admit there COULD be something wrong with my ear and that
somehow in the entirety of my long life no doctor ever detected it in
a check up or something, but that is a slim chance. So my last
question is, is there a medical condition that could explain this? And
how could it go undetected?