Why? Because the grass type and grow zone can support low cutting heights. This may not be the case in Kentucky and the question can be better answered if the grow zone, grass type, and mower type is known.
Kentucky is different than many areas since seed suppliers suggest both warm and cool season grass types and recommend, ironically, turf type fescue over Kentucky bluegrass. Local Universities often have the best information.
AGR-52: Selecting the Right Grass for Your Kentucky Lawn
Table 1. Mowing heights for Kentucky lawns.
http://www2.ca.uky.edu/agc/pubs/AGR/AGR209/AGR209.pdf
Grass species Optimum height (inches)
Bermudagrass 1.0 - 2.0
Kentucky bluegrass 2.0 - 3.5
Perennial ryegrass 1.5 - 2.5
Tall fescue 2.0 - 3.5
Zoysiagrass 1.0 - 3.0
I am beginning to transition my lawn to a Colonial Bent Grass / Fine Fescue mix and plan to mow at about 1 inch and may test it even lower the fall. Western Washington has mild weather and plenty of moisture most of the year. My growing zone, grass type and powered reel mower allows close mowing that is not likely practical in Kentucky depending on the grass type planted in the referenced lawn.
This was taken yesterday and is 3 weeks after scarifying, core aerating, top dressing, leveling and over seeding. It is thinner in spots than the picture shows but it is filling in nicely and mowing at 1 inch should pose no problem and lower cuts are possible for my blend.