An excellent explanation of why air to the roots of plants is so important.
When I first planted my present garden, a nurseryman planted all the trees and shrub. He took each tree and shrub out of its pot, stamped on it with his boot, turned the root ball and gave another stamp. I was horrified! He explained that it was necessary toAir-root break up the roots. I lost only one tree due to root death.
I read and watched videos about this last year (I think you were the one that pointed to them). I plan on drilling many holes in my pots this year before planting in them.
I think this 1.5 minute video explains it concisely: