It's confusing and goes to the crux of the question being asked, in the old days when you had to buy a ticket from a station it was relatively simple, but now when you buy an online ticket and select the appropriate railcard discount, are you you buying the ticket with the railcard you already hold or are you buying a ticket which you will only use accompanied with a valid railcard? The latter, in reality, I think.
When I'm 60, in a couple of years, and I get tickets bought for me by the charity for whom I do a little voluntary work, why wouldn't they do so with a railcard discount if I tell them I've got one? Technically, then, do I have to buy the ticket myself and claim reimbursement from the charity? But they want to encourage me to do work for them so they're more than happy to buy me rail tickets which I can use in due course.