Process praise builds trust, because the receiver feels acknowledged and seen.

As a leader even if you don't like the result of the work it's important to acknowledge the work.

Imagine the other person is trying to guess at what you want and then do it.

They put a lot of effort in but don't get to an outcome they think you'll find valuable. If you say "no that's not it" it's demoralizing.

They think to themselves, "Why did I even try"

If you acknowledge the work (the effort and expertise) then they feel validated and are more likely to listen to then be nudged.