In verse 23, they had gone out, and sent Lot to Zoar:
God determined that because this sin was so pervasive in that area, He not only had to destroy the city, but He had to destroy the countryside, and everything that grew on the ground in it. He needed to wipe the slate clean.
You almost get the sense that the whole place was just stinking with this perversion, and He wanted to remove the scent—just totally remove it.
It is funny using those terms. He did it with fire, and brimstone, which has a sulfurous odor. God would rather smell that than what came up to His nostrils from their sin. God clearly links these particular sins—these perversions—with His wrathful and just punishment.
