GILDING A BYZANTINE MURAL ON CANVAS

It's either a feast or a famine but I am fascinated by this icon-painting onto canvas. I've heard it's not uncommon in Greece where the painting is done on canvas in the studio and then pasted to the wall of a church. Not as permanent and more easily damaged but cheaper for the client and more convenient for the artist. Oil gilding canvas is something new to me (don't think water gilding would work) but the effect looks good. What would our churches look like if they were covered with pictures of the mysteries of our faith? Why are white walls or brick work so common now? Is that another effect of the Reformation?