Unsure how this is playing out in practice now it has been up and running for a bit on LNER etc, but I just booked a ticket with EMR for some unavoidable travel in about 10 days time and purchased Advance as secured a significant discount.
The online EMR booking went through the steps of asking me what type of seat I wanted (window, table etc) but when the actual ticket booking confirmation came through although it makes clear I need to be on that train is states that:
"The passenger is free to sit in any vacant unreserved seat for the class of travel specified on the ticket"
Not collected the actual ticket yet so not sure what it will say on that.
I assume that this is because EMR's software for seat allocation is not up to sitting people in seats dotted about with suitable distance from each other (and obv I realise EMR is not making services reservation compulsory)
I guess LNER / WC etc are able to do this (or does the reservation system just allocate people first come first served so everyone is all sitting in coach A and the rest of the train is empty....
)