Kakashi can go underground and Madara's PS destroys mountains.
Kakashi can warp PS's hand/sword but, it comes right back because it's just chakra.
Obito knows about izanagi, who do you think told him about it? Madara.
Madara can use a wood clone when attacking just as he did with the Gokages.
Obito can't beat EMS Madara. He can only go intangible for 5 minutes and if he warps him into kamui it doesn't solve the problem.
kakashi would go underground to avoid coming fire and get out quickly
madra can't use fire while using perfect susano because susano would block it and the height of perfect susano would prevent the fire from reaching kakashi who on the ground
if kakashi warped susano's hand ,it won't come back easily ,susano has never renewed in manga ,even if it has renewed before ,that won't be quickly
if kakashi warped madara or part of him ,the fight would end,
obito can go intangible for 5 min continually ,madra can't make him intangible for 5 min
obito can teleport behind madra then warp him or use rinningan's ninjindu on him
if obito warped ems madra to other dimension,he would starve there
ems madra can't use wood clones ,edo madra is the one who can