If there's a problem that can't be solved for a while there's world of difference between saying "Your code is wrong. This is a problem we can't solve for weeks." and "You've made a great start and this code is going to be really useful as a foundation to build on, but there's a new challenge we didn't foresee so we'll need to make a couple of changes when we have more data."
I've never met a technical problem that couldn't be solved better with good people skills. Knowing how to get good work from people is key for any tech business.