I’m glad you asked, let me give you some insight! First off I will tell you what thatch is. It is generally a combination grass clippings, leaves and other organic material. Even if you bag your grass every time you mow, you will still have thatch build up, but way more so if you mulch your lawn.
Are there benefits to having thatch in your lawn? Yes, definitely! As the thatch breaks down and decays it releases nitrogen into your soil which is essentially fertilizer. It can also help protect the lawn from extreme temperature fluctuations, and some foot traffic.
However, if you have more then a 1/2 inch (1.25cms) of thatch buildup, that is when it becomes an issue.
To much thatch in your lawn will cause the grass roots to not receive enough moisture, air and nutrients, and essentially suffocate. It can also becoma a breeding ground for pests and harmful fungi.
The main reason you should dethatch your lawn is to maintain a healthy and lush lawn