I think it's mostly anecdotal (I have heard it too, but I can't think of where)

Not a metallurgist, but if I had to guess it was hard to find in large enough quantities at the time. I also understand that it's a lot harder to work with than say aluminum or steel

Speaking of which, King Louis served his guests with aluminum silverware, since at the time it was more valuable than gold due to the difficulty of extracting it at the time, despite its abundance.