For sure is about whether the buyer does his research or not - as far as "numbers matching" - I have reached out to several posters on here who did not realize there are FOUR places on a P14 that have the serial number stamped - not just on the bolt handle and on the receiver. And then most all of the rest of the 80 odd parts (coil springs and screws normally excepted) have a maker's stamp that ought to go along with that receiver, to be "all matching". Such a thing might not even exist any more - but does not make a random rifle that happens to be at hand to be worth what some of us would pay for a genuine "all matching" - and there should be a LOT of questions to establish that to be genuine, before money changes hands.
Versus poorly done (or well done) milsurp conversions with bolt handles cut to be "scope friendly" and the receivers drilled and tapped, yet the rifle described as "ideal to restore", or not obvious at all how the original "swing over the top" safety was supposed to work when a scope gets installed. Is up to the buyer - sooner or later someone gets left holding that "hot potato" - whether that buyer, or someone he can sell it to. But I think is all on the buyer - they bought what they bought at whatever price - and got what they bought - whether that was what they thought it was or not.
Might be a shocking thought to some people, but some of us have many hundreds or thousands of dollars of reference books, that allow us to sort though what belongs with what - if those authors were correct. Or some will spend silly amounts of money, and just claim it to be what they think it is. As an example, for the common Lee Enfield No. 4 or No. 5 rifle, was 9 receiver patterns used at one time or another, 9 different variations of rear sight used by the six factories in various years, and at least four different kinds of wood used - and most all will interchange with the other - so is a specific combination that goes together to be "correct" and then multiple combinations that "work", but never existed in anyone's military.