Comment by cryostasis

I think regardless of implementation, if the added complexity reduces reliability and introduces forced failure modes it's reasonable for people to avoid these systems altogether. For example, EGRs causing fouling or DEF engine throttling.

This may be true for our group, but I know numerous blue collar workers at the poverty line struggling due to these systems. Corporations / manufacturers have no incentive to make these systems more accessible. Even if they did, more complex -> more expensive to repair.