"Rav Schwab is quoted (in his son's sefer) as asking, why do you have to repeat shmoneh esrei if you skip Mashiv haru'ach umorid hageshem? Not every word in shmoneh esrei is essential, as shown in havineinu, and here, we're not even asking for rain, it's just a mention of the gevura of rain. He answers with the Gemara in Chulin brought by Rashi in Breishis 2:5. The passuk says "Now no tree of the field was yet on the earth, neither did any herb of the field yet grow, because the Lord God had not brought rain upon the earth, and there was no man to work the soil." Rashi says..."
cont. Beis Vaad L'Chachamim