Because it seems to be working for me.
I have to press ALL the seams open on these blocks I am working on (and not liking it a whole lot).
The other day as I was pondering open seam I decided that it might be easier to do if I wasn't working on a flat surface.
So I pulled out my old ironing 'ham' - and it does seem easier...
But like I said - if this isn't true - don't tell me until I am done.