Verticutting - cleans, thins, removes thatch, and improves mowing 

"There are myriad benefits to Verticutting, which has also fueled its popularity. Jeff Buchko, a product manager for Jacobsen lawn equipment, says more university researchers have concluded that verticutting is a cultural practice that's critical to turf care" 

Why Verticutting:

St. Augustine grasses
The dominant grass in central and So. Florida is St. Augustine. The excessive top growth, along with the accumulation of thatch creates many problems.
While cleaning & thinning your lawn, Verticutting allows your lawn to breathe again, stimulating root growth. Opening the lawn-up allows air, sun, water, and fertilizer to drive the root system deeper, thru removing the top growth and thatch. This vastly improves mowing.

All grasses accumulate thatch, see thatch