Oh, steam is a good thing when you want to shape fabric into say, a garment sleeve cap or a art project you wan to form into something. But, if you use steam and are working with bias cut quilt block pieces, you are risking the piece to stretch out of shape. I think you get the idea
The other thing to mention here is pressing seams open is an up and down motion, No Scrubbing on the fabric. Fabric is easily misshapen with steam.