It is extremely hard to retrofit a truly multiplayer interaction model onto a single-player product.

Unfortunately, making something multiplayer from the start makes it an order of magnitude harder to get to the first moments of micro-PMF.

Figma took years to get their first product out the door, because they saw that a multiplayer foundation was critical to their success.

Multiplayer is a matter of degree; it's possible to have something more or less multiplayer.

For example, Google Sheets is multiplayer… and yet if two users edit the same cell at the same time, the last write wins.

But because it's chunked down so small, it rarely happens in practice and it's fine.

Another way to get cheap multiplayer: only allow one user to edit, but allow everyone else to comment.

Comments make it feel multiplayer, but have few coordination issues, because each user can only modify their own comments.