Universal Cottage - moving stairs if using I-beams?

[Charcoals]

I bought the Universal Cottage plans a few months back, and in scouring old posts, noticed a comment that if one uses I-beams, one can position interior walls wherever.  This was not news to me.  However, the comment also indicated that the stairs may NOT be moved, even if one uses I-beams.  Why is this?  If the engineered I-beams are carrying the loads to the outside walls, what weight-bearing purpose do the stairs serve?

I'm probably missing something embarrassingly obvious here (wouldn't be the first time). 

Thanks in advance!

[John Raabe]

The stairs can be moved where ever you want. It will, of course, involve changing the stair opening in the 2nd floor framing of the I-joists (and in the main floor if you have a basement). That opening can be slid forward or back and moved from one side to the other without structural consequences.

Note: I'm assuming you will use the "U" shaped stairs in the plans that has a rectangular opening. You can get into having to have a post when you do an "L" shaped stair. But this too can be relocated when the stair needs to move.