That's most of it. It gets lost in the right to repair conversation, I think because many of the same individuals who care about that also tend to be very pro-environmental-regulation, but one has to take a step back and acknowledge the fact that the EPA made it illegal to build this tractor new instead of with a rebuilt truck engine from the 90s. You literally cannot build a legal diesel tractor in the US that doesn't involve an ECU, sensors, DEF, and all the proprietary electronics to go along with those systems.
If it was legal to build these at industrial scale, we'd already have it in the US because there's blatant market demand for it. This is functionally no different from the shops putting 30 year old diesel engines in modern pickup trucks for the same reasons.
The emissions are so unreliable that the only legal market for vehicles without them in the US is... the federal government.
The decision to lock down the ecu is quite another thing.
It could easily have been done with a basic ecu that was readable by a $20 cable to your laptop.
That being said, the DPF is the destroyer of modern engine reliability.