your questions regarding the game rules (improving the interpretation).

It would be better if only simple units appeared in the Grand Order!

No, it's just that this is the only Grand Order that actually forces you to spend 2-4 extra days searching for something (flying over to resurrect, killing others) and, at most, makes it impossible to complete – it's been a long time coming!

Added 2 minutes later

P.S. And why specifically Sultans? Why not Fairies?

Because with a large army and several powerful stacks, Fairies fall quickly. As for Sultans, they are an almost unbeatable unit for Barbarians, Swamps, Inferno, and less frequently for Fortress and Conflux – I'm talking specifically about Grand Order!