Engineer: So are we changing the nav icons as part of this story, too?
Designer: Oh, no, ignore that. I didn’t have our real icon set so I just grabbed some others
Engineer: This modal doesn’t look like our normal modal, are we supposed to be building a new one?
Designer: Oh, no, ignore that - I’m working on a design for a new modal and I just used that here
Engineer: Ok, do you know our current modal doesn’t support X, so this part of the interaction won’t work?
Designer: Oh, okay, I’ll go update the design I guess
Etc... sometimes makes me wish for the days of Balsamiq / sketch style designs where the idea was to not try to make it photorealistic.
Having said that I guess if you could get Figma completely in sync with your actual UI it’d be pretty nice.
EDIT: I will add that the clickable mockups seem really helpful for our Design team when they're doing user testing, which is happening before the designs get to us. But this is not unique to Figma, InVision can do it, too.