Haven't worked on a video game but was unlucky enough to work through many small crunches in other industries and it's always a combination of lazy people and mismanagement.
Some examples:
1) I have a task A. For the task A, I need info/mock-up/foundation from person Z. Person Z claims to be busy with other tasks or waits for someone else. I think person Z is a lazy fucking idiot who's only good at making excuses but project team doesn't object so what can I do. Therefore I proceed with other tasks to enjoy crunch before deadline.
2) Here are tasks B, C, D, and E. B is an important foundation many other tasks are built on and was quickly hacked together at the start to have a minimal viable product to work with. Task C, D, and E are partially (or even fully) reliant on task B. Project team focuses on tasks C, D, and E.
"Hey, project team, shouldn't we focus on task B for a short while, to clean it up and flesh out other functions we need, so we have a smoother process with the other tasks and avoid waiting for dependencies?"
"Are you crazy? Those are important extremely high visibility tasks that need to be shown to the CEO/board/director/customer/whoever. Otherwise, there would be nothing to present!".
Aight ya fuck but don't say I didn't warn you.
3) Here we have 20 small tasks that would take 2 - 3 days to complete and more small tasks keep piling up and are going to be a huge annoyance once deadline comes. Some require collaboration and decision. Perhaps we should do them now when we have a bit of a breathing room?
"We can't afford dedicating our resources to these small tasks when we have the big ones here.".
4) "Hey, how is it going with that big task you're working on for half a year now?"
"Yeah, they changed their vision of the final product, which means we're starting again. For the third time now."
5) "What are you working on? Shouldn't you be fixing the bugs we got from quality?"
"Yeah, but the boss just stopped by with a new feature that needs to be ready for the presentation next week. He said it's for the big guy and extremely important. You know how it is."
"Yeah..."
And tons of others I could come up with. It always comes down to working with idiots.
The moment deadlines comes, suddenly, everybody is extremely efficient, no one is coming with useless reworks or adding useless features to please higher-ups and small decisions are made by individuals as they can't afford to wait for approval with every bullshit.
I'm sure it's absolutely the same in vidya industry.