You must take into consideration using larger and thicker pieces for stability and of course provide an excellent sub base for setting the stone upon.

We have installed dry lay and wet set stone patios and pathways for over 25 years with excellent success.
Prior to having my own design+ build company I observed my grandfather and uncles installing masonry projects .
Their dried laid masonry work can be seen in Copley Square of Boston which was done close to 100 years ago.

Good design is timeless.. and quality installation work will stand the test of time.

Concrete is not that strong on its own. It requires tensile strength. The rebar metal adds this strength.
It is considered a standard application from masonry professionals when pouring a wet set.

If you were quoted a price without the metal and you live in an area that the ground freezes or you have earth movement either from earthquakes, liquidfaction, heavy clay soils ect... ( which includes just about everyone unless you live on a granite boulder ) you should always put metal reinforcement in your concrete footings and slabs.

If you are going to hire someone to do this job for you , you should look at their portfolios of recent work and or at the very least look at several of their jobs so that you can see the quality of their work.

Personally, I would not be going into a hardscape project like this without any written specifications to hand over to the contractor.
If you don't have any spec's you are leaving yourself wide open to the individual contractors interpretation.

and that can be disasterous.