What is the for and against argument for the volcanic theory?

The reasons for the volcanic theory are that when volcanoes erupt, they send huge clouds of dust, sulphuric acid, and poisonous gases into the air making the air almost impossible to breathe. The dust and ash in the atmosphere would also change the climate and sunlight levels. On top of that, the ground would be covered with layers and layers of molten rock. The dinosaurs would never have survived such a hostile, poisonous environment. A huge increase in volcanic activity at around 65 million years ago could have pumped so much ash into the air that it blocked out the sun, killing the dinosaurs.

I am not sure on the reasons against, however I do believe that the asteroid theory does have more evidence backing up the theory.