My DW used to work for a county road department before retiring and at any one time up to 25% of their diesel trucks of all classes were out of service due to emission system failures. Many small fleet hot shot operator's have been forced out of business because of repeated failures of late model emissions system's. Larger OTR fleet operator's around here have had to buy up to 25% more tractor's because even the big class 6 tractor's have DPF and DEF failure's.
Between environmental wacko's and overzealous government bureaucrats mandating regulation's they know nothing about from an engineering and technical basis they have completely screwed up diesel engine's. Until downstream emission control system's are perfected deleting DEF and DPF system's are an evil necessity for many individuals and entities. Condemning people for doing things that they must do to survive ain't cool.