Imagine that you're a highly intellectual, highly technical, and highly responsible person in control of large sums of governmental or corporate money. You don't want to waste the money, you want stellar results (in spacecraft industry, maybe literally so).

Would you assign a large sum of money to a group that cannot present their design clearly, neatly, and concisely? If they are struggling even with that, would you trust them to be good at actually designing a spacecraft soundly, economically, and in a reasonable time?

"If you can't explain it to a five-years-old, you likely do not understand it yourself", said one of the greatest modern scientists, who also was notoriously good at explaining things.