The history of a design proposal is, in fact, sometimes a relevant argument for or against it. It can say something about the uncertainties (“unknown unknowns”) around the concept.
When an idea or design concept has been put through criticism, when it has been poked, prodded, changed back and forth, there has been a process of discovery. Were there any unexpected behaviours, properties, interactions, etcetera?
When we are presented with two proposals that seem comparable in terms of predicted performance, but one has only been drawn up yesterday and the other has been the subject of development for significantly longer, even when the final level of detail is similar, the ‘younger’ idea can be legitimately opposed simply on the basis that there might very well be something wrong with it while the other one can be accepted with less risk.