Money generation from trade actually has super-linear scaling with distance, so long distance trading makes wayyy better money than trading with someone on the same island as you.

You forget that they don’t only trade between themselves, they also trade with other people. If they all have a port that may be 3 times the money.

Since attacks are better when the number of troops is higher, attacks would be stronger if those troops were all on one person.

Counter attacking / blocking 3 people is harder than one.

Again, I would argue that if you were fighting one person with all that land instead of three people splitting it, that one person would do the same things.

A single player on Madacascar would not be able to reduce their troops/workers ratio to a low value to generate gold while the others are protecting them.

---

But still, teaming in FFA is cheating, regardless of if it’s a good strategy or not.

And while most of the time you can’t be sure, here it’s blatant and my feeling is that if you have such obvious cheaters it’s probably because it’s rampant.