Why some types of banana trees seem to grow better when I leave the dried leaves on them?

Question

I always thought that leaving the dried leaves was good, according to my experience, but then I saw on google that cutting the dried leaves stimulates growth, so I'm confused. I noticed that the dried leaves protect the stem from being dried up by the sun and conserves moisture in the soil and the plant grow faster. I also noticed that not all types of banana trees need the dried leaves. I also think that there should be a purpose for the dried leaves, because everything in nature is for a purpose. When I cut the dried leaves, I notice that a brown layer forms on the stem but when I leave the dried leaves it looks smooth and with the colour that it should have.