I think the biggest problem with the "big function" is that it tends to lead to code duplication. If taskY is in bigFunction, but taskY is needed in otherPlaces then people tend to just copy paste taskY in otherPlaces.

If another developer joins the team, then he might not have noticed that there is a taskY and may end up writing his own, completely different, implementation in yet another place.

For C, I tend to go the big function route but I usually try to put extra braces with comments to isolate subtasks from each other within the big function. Then I can pull out the tasks into functions if I see that I need them in more places. I don't know how my old code is doing so I don't know if anyone has followed my lead in those projects.