If it was, that is. I think I’ve read somewhere that it was, or rather the large slices or fancy stained glass was. But, why? Was it because they didn’t know how to make it, and just found clear slices on the ground? Or was glassblowing hard to perfect? Technology was insufficient to make the large panes?
TLDR: title says it all. I hope this is on the right subreddit.
Stained glass is expensive now, first off its art so it's not just a product it's something that is unique. Secondly making pains of glass definitely wasn't easy and colouring the glass definitely wasn't. Finally the frames the stained glass goes on was made of things like lead and that was expensive too.