Random selection of indefinite DLA claimants to P

I just do not get this at all.Having completed their "Pilot reasssments" in chosen postcode areas, the DWP say they are going to implement Natural reassessment of existing indefinite DLA claimants nationally now;but randomly choosing claimants to reapply for PIP.
Surely what this means is that it will be far from random,with those who perhaps got DLA in the early 90's before the process was made stricter in recent years, or those who turned 65 after April 2013.(The latter group being specifically mentioned by the DWP as being invited first to apply ) being actively selected.
Why random,and why are the DWP simply not undertaking Natural reasssement in say alphabetical by surname order?
Despite the DWP claiming that they are now in a position to process 2,000 applicants a day, what all this clearly means is that there is no way 4. 8 million claimants are going to be processed in 2 years.
The approach by the DWP is therefore piecemeal,fragmented,unfair and will extend maybe well into the next parliament .
Those genuine cases who ought to have received PIP may well have been denied this benefit, whilst large numbers of DLA claimants who may not be so deserving may well find they are still getting DLA after 2020.The whole thing an unfair unending fiasco ,with the most needy often suffering

Since when did the DWP do anything in a rational, logical manner?? I expect the PIP roll-out to be a shambles, as was the ESA.

I am going to leave this thread open for now. However, one of my mod colleagues will lock it if it appears to be turning into a discussion.