This is a good answer.

At my job, there was a desire to do a big rewrite of the system. It was a disaster. We spent like 8 months on this project where we delivered no value to customers. Then there was essentially a mutiny from the engineering team and we killed it.

We've since built on top of the original system and had, in the words of product leadership, "the most productive quarter in the history of the company".

Now, why was it a disaster? The biggest reason was that people, especially people in leadership positions, did not understand the existing system very well. They would then make decisions based on falsehoods and mythology.