This is true but it's much easier to understand in retrospect unless you have a very very gifted math teacher (or series of teachers really) when you start learning it. For most people learning algebra it's just another checkbox to tick for some reason. Plus pesky word problems that make you figure out the equations on top of that.

Now that I'm an adult I recognize what all of this was trying to teach me. But back in my school days it was just another thing I had to do between hanging out with friends.