As a designer who has been part of small and large teams there is a critical problem is solves which makes it worth it: Versioning.
Versioning is hell, there are git-like solutions like Abstract or Cactus but aside from those solutions being half-baked, the need for versioning at all disappears with multiuser/multiplayer. You have one doc, one source of truth. When I work with other designers, PMs, copywriters, etc. Who all need to make edits for one reason or another, it because a nightmare really quickly.
The fact is 99% of the time, you'll be in the file alone. Just like Google Docs. But when you need it, it saves you a lot of time.
Versioning is hell, there are git-like solutions like Abstract or Cactus but aside from those solutions being half-baked, the need for versioning at all disappears with multiuser/multiplayer. You have one doc, one source of truth. When I work with other designers, PMs, copywriters, etc. Who all need to make edits for one reason or another, it because a nightmare really quickly.
The fact is 99% of the time, you'll be in the file alone. Just like Google Docs. But when you need it, it saves you a lot of time.