Traditional math instruction has convinced the world that math is about manipulating naked numbers quickly on command. For too long, students have been led to believe that math is something you do in isolation of the real world. And so many of us have come to see the best way of doing math is to simply follow the instructions.
It should be no surprise that these kids grow up into adults who perpetuate their own experiences with math on to their own children (or teachers to their students).
If algorithms are all a learner really knows, it's hard to see math from a more sophisticated perspective. It's not easy to recognize that the algorithms we received through direct instruction are manipulating both the numbers and the learner.