Thank you for that additional information. It only makes good sense.
I recall that period post VCII. Many churches, in their haste to erect an altar "facing the congregation", opted for wood which could be quickly assembled. Now, 40+ years later, the Vatican has issued a reminder to replace those altars with more permanent ones.
Even (can't remember his name, memory is getting bad), the priest who sneaked into England and got into trouble during that bad time when the throne went back and forth. You will know who I mean. He even had proper vessels hidden away to celebrate mass in the Tower, was eventually martyred. I looked it up, think it was St. Edmund Campion.
I may still have that book, but one other case comes to mind. And I don't necessarily blame the priest, but he put a consecrated host I think it was in his breviary to take it to a sick person, and it started bleeding. I think they were supposed to use a special container, some will know what that is called. The book didn't make my point, and I might be wrong, but I kind of put 2 and 2 together later when we used to discuss all the liturgical abuses.
But most times considering all the accidents and other liturgical abuses, it doesn't happen. I may still have that book and IIRC the wooden altar was used temporarily when they were doing something with the main one or work in the church.
Maybe we need to look where all it has happened, don't recall any cases in the Americas, a hoax one that was pretty disgusting in Keene, NH.
Good, I'm glad the Vatican finally issued an order about the altars, hope they obey it. Some things we just can't know the reason for sure. Good points, all of it.