I didn't intend for it to seem like 'random souls', but people that yevon had lured to begin the aeon process. Like I said, I think they add up overtime (a little piece of all the previous fayth that had become Sin, while the largest piece of Sin is the latest fayth), which would give them a connection with zanarkand..

Or perhaps it's just Yevon reliving old times.

However, I think it's lulu tells us that fayth are specifically the people who give up their still living souls to become encased in stone [to become the aeons]

What's more ironic about yevon-worship is that all the maesters in Spira (well the dead ones anyways(well, mika I guess)) knew about it, but continued the practice so they could keep their high status.