Why are Resumes now confined to one page?

Way back when in 1997 when I got out of the Army doing a Resume was easy with 2 pages. Now they make it REALLY difficult with the one pager rule. Why is this so and what promted the change. There's so little room to make myself stand out from everyone else. I want to be the one they hire so I must be different and make mine stand out! Thats hard to do in one page.