How Do You Do

She said "How do you do".
Did she say that with a question mark? I understand that the proper answer to "How do you do" is "How do you do". So I would think it doesn't require a question mark. Not a question if you ask me. You answer a question with an answer, not a question.
What does it mean?
It's a greeting.
I've read it's from the English upper classes. The separation of U from non-U. The U contingent had napkins, lavatories and greeted people with "How do you do". The non-U's had sleeves, toilets and greeted people with "hello".
Hello I can understand. A simple greeting. I guess I'm just a non-U. But How do you do? How do you do what? People try to tell me it stands for "How're you doing?" And I say doing what?
The Internet says that the early meaning of the verb "do" is to prosper, thrive. How do you prosper? How do you thrive? That's a question you ask everyone everytime you meet them? Sounds rude to me. Naw. Most of us don't care. We say "How are you" just to keep from being awkward. We don't really want the other person to tell us how they are. What a waste of time.

I have a different take on how do you do. It started out long ago, way back when. Back when nobody knew how to do anything. Nowadays you can ask a friend or read a book or get on the Web and find out how to do whatever you want to do. The only way you could find out how to do what you needed to back when was to ask someone else. Everybody was trying to do things but few people knew how to do them.
This was back when. When was a time of unknowing, of undone things. So when you met someone. When you met anyone, you had a question of how to do something because you knew how to do practically nothing. So your life was full of questions about how do you do this and how do you do that. Until shoes were tied, no one knew anything at all about tying shoes. So you had to ask. That's why there's so many shoes out there that don't tie. Shoes were made for centuries before anyone bothered to figure out how to tie them. Until grub was cooked, you didn't know anything about cooking it. So you went most of your life eating raw foods because when you walked up to people and said "How do you do?" And they responded with, "Do what?" and you said cook? They said "What the hell is that?"
So anyway my point is, that's what how do you do means. It was simply the common question of the past when nobody knew how to do anything so they greeted each other for centuries with the question of how to get things done.
It made the world what it is today.
How do you (waste precious time?). You just did.