Health: The crops would grow without irrigation, as long as there was water supplied. Irrigation is simply an easy way to supply water.
Before the Jews regained control of Israel, there was nothing growing there. The arabs had turned it into a wasteland. Now the land is thriving. Why is it common sense to say that it means without irrigation? Do you have a source other than your own (twisted) common sense? Maybe R’ Yoel said it?
I’m also wondering how you will twist the nevuah of Od yeshvu zkenim u’zkenos b’rchovos Yerushalayim. What does that mean? Sitting without chairs? Or maybe only sitting on gold-plated thrones? Because it seems to me (via common sense) that the nevuah has been fulfilled.