It's actually very easy to do un rhe engineering sense. These latest gen diesels emit less particulates than most petrol cars, the performance of DPF's is so good. Even early DPF's 20 years ago could be so good they wouldn't trigger the machine at MOT time.
Of course, making them both reliable and human proof are a different kettle of aquatic life altogether.
Adblue doesn't affect particulates, is a measure for Nox reduction and is highly effective. They can indeed be unreliable, but in the grand scheme they're not so bad - after all, people don't come on here and start threads about how excellent and trouble free their AdBlue system has been this week. If there's nothing to report, nothing gets said, so the type of background noise we hear is vert skewed.