LNER are very keen for passengers to get Advance fares, especially more expensive through fares (no splitting) and from their website.
The idea that someone may get flexible fares and/or cheaper splits and/or buy through our ticketing site seems to horrify them.
Hence, their advertising campaign (at taxpayers expense) aimed at misleading people into using their site instead of sites such as ours.
This airline-style pricing is how the DfT and people like the (now disgraced) Peter Hendy want all TOCs to be run