Imagine you have no religion, but are feeling spiritual and want to find something real. Do you go to the church of a religion that claims it has the actual remains of their saints, or the one that only has pictures and empty walls?
Actually, maybe that's a stupid question as people absolutely do both. But there is an element of "look how great we are because we have a splinter from the holy cross in our church".
I don't really think I got your point. All "evidence" that the bones in location X are really those of St. Y, won't have any effect on you, when you don't care about St. Y at all, because you don't believe in that religion.
I can't follow you here. Relics only have a meaning when you already believe them to be relics and no just random bones. How is that advertising?