Chance would be a fine thing. Last week I tried to book tickets online for a journey from a South London suburban station to a town in Kent. Two trains, changing from Southern to Southeastern, if that makes a difference. The only options online were to print out tickets at a TVM, or to have them downloaded onto a card - I've forgotten its name, but it appeared to be a SE specific 'Metrocard" - which I didn't and don't possess. So knowing that the starting station had a staffed ticket office I decided the simplest and safest method (not being sure if the TVM would work) was to buy tickets in person. Unfortunately the member of staff got confused and mistook a Senior railcard for a Freedom pass (but that is another story) adding to the complications. But I could easily imagine that an ordinary member of the public trying to buy online could have similar complications. There is no substitute for the human touch.
This is another unfortunate example of a disintegrated rail network. If all TOCs played by the same rules, and all issued E-tickets as well as the option of buying paper ones, plus any other options they care to add in, we'd know what we were doing and people might accept the closure of ticket offices. As it is, the systems are all too confusing for ordinary mortals.