If by "this", you mean "getting rid of return tickets" in the way DfT/LNER have done, then I can't see the reasoning.
I have looked again at the main thread where you make the same point - but also refer to other flows, like York to Northallerton, where return fares haven't been got rid of - pointing to the high level of single fares.
Yes, those single leg fares are high, but I don't see why the cause of that is; "getting rid of return tickets", when they are the very flows where return fares remain.
I'm not sure what you are trying to say; if you were saying that those fares were not part of single leg pricing, I did reply to say yes that is indeed the case (as described in the original thread)
If you are asking why LNER have done it this way, again without LNER or DfT explaining the reasoning, we can only guess.
Having followed the main thread I remain puzzled by this specific criticism of single leg pricing, but as you have nothing further to add, that's fine.
If by 'this specific criticism' you mean the fact that 'shorter' distance journeys have generally not seen a reduction in the cost of single fares, then I don't understand why you are puzzled by that criticism, but you are entitled to your views of course.
I would support single leg pricing - despite loss of rights such as enhanced Delay Repay and break of journey over multiple days - if
all returns had been exactly
halved, without exception and without abolishing fare types. (Where this would have resulted in superflous fares, the more expensive could have been abolished)
But that's
not what we got, and unless there is a major change of policy at DfT, that's not what we are ever going to get!
This has all been discussed in the previous thread.