Try discussing this then:
AWS D1.1 -2004 section 4.26 page 127. "CJP Groove Welds for Tubular Connections"
Welder or welding operator qualification tests shall use the following details:
(3) For CJP groove butt joints, or T, Y, and K connections with backing in box tubing. - Use fig. 4.25 in pipe, (any dia), plate, or box tubing.
Again, as long as you use backing-whats not to like?