Yup. The two things John Deere did was make it impossible to diagnose problems with software lockouts and they did software locks for common parts. Imagine, for example, needing to pay $1000 to replace an oil filter because you needed to buy the official John Deere oil filter and have the John Deere technician drive out to install it and flash the tractor to start up with the new filter.

That's what John Deere was up to.

Also, I'd point out that tractors are, by and large, actually pretty simple machines. At their core they are an engine and a hydraulics system. Not much more. The most fancy tractors will obviously have a lot of creature comforts in the cab. GPS, auto steering, AC, etc. But the actual things that do the thing are effectively just solid metal parts that plow through the field or cut down the crop.

Tractors, because they are so simple, but also because they all operate at lower speeds than other vehicles, are almost immoral machines. My family literally has a John Deere from the 40s that starts up just fine. We also have a Massie from the the 70s that still operates just fine. And our newest Massie from the 00s is still doing farm work. The only reason we got the Massie in the 70s was because it had more horsepower than the John Deere from the 40s. And the only reason for the 00s tractor was because it had a closed cab with AC and more horsepower.

It would not shock me to learn John Deere was also integrating some planned obsolescence to speed up the turn over of their tractors.