Excellent point Harry. I think about it! The book of Zechariah has something to say about it too. I realize EGW never mentioned it but hey.
Behold, the day of the Lord is coming,
And your spoil will be divided in your midst.
For I will gather all the nations to battle against Jerusalem; And it shall come to pass that everyone who is left of all the nations which came against Jerusalem shall go up from year to year to worship the King, the Lord of hosts, and to keep the Feast of Tabernacles. And it shall be that whichever of the families of the earth do not come up to Jerusalem to worship the King, the Lord of hosts, on them there will be no rain. If the family of Egypt will not come up and enter in, they shall have no rain; they shall receive the plague with which the Lord strikes the nations who do not come up to keep the Feast of Tabernacles. (Zechariah.14:1-2, 16-18)
The leaves of the tree were for the healing of the nations. (Rev.22:2)