If everyone is surprised, no one is

It doesn't matter whether it's possible or not. There's probably enough room for a GM to decide that everyone in an encounter is surprised, but it's not an interesting situation. Let's look at what happens when the GM decides it happens:

1. Everyone rolls initiative
2. First player has a turn. They can't do anything but lose the surprised condition.
3. Second player goes, can't do anything either.
4. Keep going until everyone had a turn, each participant doing nothing and losing the surprised condition.
5. First player goes again, but no one is surprised anymore.

Ergo, if everyone is surprised, no one is.

If everyone is surprised, no one is

It doesn't matter whether it's possible or not. There's probably enough room for a GM to decide that everyone in an encounter is surprised, but it's not an interesting situation. Let's look at what happens when the GM decides it happens:

1. Everyone rolls initiative
2. First player has a turn. They can't do anything but lose the surprised condition.
3. Second player goes, can't do anything either.
4. Keep going until everyone had a turn, each participant doing nothing and losing the surprised condition.
5. First player goes again, but no one is surprised anymore.

Ergo, if everyone is surprised, no one is.

If you want to look at it another way, the surprise mechanism allows some of the participants to get an extra turn in before the fight starts. But if everyone gets an extra turn, then no one has an advantage.

If everyone is surprised, no one is

It doesn't matter whether it's possible or not, there's probably enough room for a GM to decide that everyone in an encounter is surprised. Now let's look at what happens when the GM decides it happens:

1. Everyone rolls initiative
2. First player has a turn. They can't do anything but lose the surprised condition.
3. Second player goes, can't do anything either.
4. Keep going until everyone had a turn, each participant doing nothing and losing the surprised condition.
5. First player goes again, but no one is surprised anymore.

Ergo, if everyone is surprised, no one is.

If everyone is surprised, no one is

It doesn't matter whether it's possible or not. There's probably enough room for a GM to decide that everyone in an encounter is surprised, but it's not an interesting situation. Let's look at what happens when the GM decides it happens:

1. Everyone rolls initiative
2. First player has a turn. They can't do anything but lose the surprised condition.
3. Second player goes, can't do anything either.
4. Keep going until everyone had a turn, each participant doing nothing and losing the surprised condition.
5. First player goes again, but no one is surprised anymore.

Ergo, if everyone is surprised, no one is.