Single post in Eben is going to Paldea!

You are not required to hatch them. Only summon them. This is not a requirement at all, and anyone claiming it is a requirement is just making stuff up for no reason. Since the complaint is with regard to progression towards the Azure Flute unlock (and nothing else since nothing else is affected by this "issue"), more Boxes are going to be needed anyway to get any remaining Summon Items that the user may be missing on their quest for the Azure Flute, and to get the Azure Flute itself. Since more Boxes are needed anyway, this is also not a real concern. Furthermore, Boxes are given out for free by the game in sufficiently plentiful supply, assuming you participate in Scour Missions.