A lot of us were doing some form of agile before someone came up with the word agile.
I'll give you an example:
Imagine the process of creating a retro video game.
First, you might write a function that clears the screen.
Next, you'll get something simple drawn. Maybe just a simple block.
Then you write a function that allows you to move the block with a controller.
Then you swap the block with some sort of character animation.
Next, you'll write a routine to draw girders.
Then you'll implement gravity.
Etc., etc. You'll just keep iterating until you have a well-balanced and engaging game.
That's agile. You may have had a lot of the game designed beforehand, or none. In fact, you could even create the game design documents with the same method. Make a quick first draft, get feedback, make adjustments, and repeat. And then keep going back to it whenever you notice something doesn't work or some better idea comes along during the course of development.
Originally, agile had nothing to do with rigid meeting schedules. Or "adapting to changes," or whichever buzzwords people like to throw around.
Electric cars have electric motors. So if you attach an electric motor to an F150 without removing the gas engine, you have an electric car. And it has terrible gas mileage.
Can you really say it is misunderstood if 90+% of people are "doing it wrong"?
Is it a useful thinking framework if there is a 90+% chance of "getting it wrong"?
I would NEVER buy a tool which advertised only a 10% success chance, so why are we falling for scrum?