Laying a flagstone patio in Ohio?

Here’s the deal: We have an approximately 600 square foot square of lawn area right off the living room of my house near Cleveland Ohio, and we want to put a flagstone patio there (to take up as much grass as possible so we don’t have to mow/water it). The official word seems to be that we must set the patio on six inches of crushed limestone. I mean, everything I read online says this, and the contractors I speak with all say the same thing—you must set it on at least 6 inches of limestone to ensure a stable base. But there was one book at the library that said you can lay a flagstone patio on bare earth—even over a lawn. For a bunch of reasons I’d prefer to set the flagstones over topsoil and plant grass in between—a very rustic look with large spaces between the flagstones. My reasons are: 1. environmentally speaking it seems like waste to lay down that much crushed limestone, 2. it’s expensive ~ $2800 to lay the limestone, 3. putting down the limestone requires heavy equipment that will tear up other parts of the yard, including plant bed. So my question is this: What will happen if I grade the topsoil in the patio area, compact it with a plat compactor, then place my flagstones and fill in the gaps with compost and then sod? Will the freezing winter somehow cause the ground to contort with the weight of the flagstones? Will they sink into the ground? I don’t mind repositioning the stones every couple years if a few of them tilt or wobble. Anyone have hardscaping experience in a cold climate and know anything about this? Thanks!