The contradiction only one setting resolves
Two requirements that rule each other out, without a plugin, at least.
The guests need the view
Without a state on the wish, two of them buy the same thing. That is precisely why the list is shared
Max does not want the view
He wrote the list. If he saw every purchase, he would know the evening before what is in every parcel
The surprise guard
One switch per list. After it Max sees "a gift was bought" in the activity instead of "espresso machine was bought"
Nothing changes for the guests
They still see every state. Taking that away from them would defeat the purpose of the list
The guard only affects what the owner sees. After the party Max switches it off himself and looks up who contributed what.