You don't need to imagine, the 1940 Euston to Manchester does, owing to it being routed via Styal. Similarly the first Manchester to Birmingham (0511) and final return (2230) omit it for similar reasons. All three I suspect are for route knowledge, though without being bothered to check the VT one may fall out with pathing. The two XC services if they ran via Stockport would also be very susceptible to engineering possessions, so it removes some of the risk there, too.
But that's not the last evening train from London to Manchester. A quick perusal of NRE tomorrow shows a 23:00 Euston to Piccadilly service which does call at Stockport, so at least passengers have the option of catching the last train of the evening !