Storyboards are wonderful if you're a lone iOS dev with little need to collaborate and great for prototyping new designs. However on large projects with plenty of git merges between multiple users I think theres a good case for avoiding.
It's definitely not a good idea to have a single or few storyboards but you can even link storyboards. In my personal opinion splitting into a storyboard per main feature/area is a good balance.
I don't. It's not that hard to talk with the other devs on your team to avoid those merge problems.