I have run several end grain cutting boards through my thickness planer. Yup, I'm a contrarian.
I found that if I rounded the trailing edge of the board with my ROS, then tearout was eliminated. Since I was going to round over the edge of the cutting board anyway, this was not a problem.
Common problems that are cited:
* dulls planer blades. True, but I have found in woodworking that when I use sharp tools, they will get dull. If I'm making good cutting boards, that's part of the process. Solution: buy more blades.
* tear out. Happens, but can be minimized. Not a huge problem, in any event. Solution: round over the trailing edge before running it through the planer.
* boards break. I've never had that happen. Solution # 1: I use Titebond III glue, which is stronger than the wood
, so I've never had a joint fail after making a proper joint (Use wood that's properly squared up, follow the directions from Titebond, and keep the glue joint clamped for several hours while it dries thoroughly. Plane the board after the glue has cured *at least* 24 hours.). Solution # 2: I make boards in the "brick" pattern to maximize joint strength and minimize the wood shattering potential.
I have a DW735 planer, and it does very good work.
All of that stated, many woodworkers don't want to use a planer in this way. I totally understand and support their decision. Never make a cut that you don't feel safe making.
After making & selling cutting boards for a couple of years, I did buy a Jet 16-32 drum sander, and I have stopped using my planer to flatten the boards. Now, I'm just burning sandpaper, which hurts my wallet as much as buying new planer blades.
Your mileage may vary, of course.
Check out the boards I'm making, and selling primarily at Southern California pop-up events, here