ACtually that's what the first study said. That we could consider allowing obese women more time to labor in first stage because it appears to be part of normal variation for them. Same with stage 2 - the studies actually came down on the side of the obese women and said they could push as well as everyone else and didn't need any intervention just because of their weight.
Yes it certainly does and I wasn't saying it didn't say that..... but can you REALLY see obstetricians and other birthing professionals ACTUALLY letting larger women labour longer? I got told by my public ob who hadn't even opened my file and had never set eyes on me in his life, that because of my size I would have a Csect. I had a 95% chance if I was really desperate to attempt labour, but he wouldn't suggest it. I bawled.
Thankfully all but 3 hours of my 38.5hour labour were spent at home allowing me to do what I wanted. I was too stubborn and I had more faith in myself than most, to allow someone to bully me into full blown intervention. I was able to avoid everything but the gas although I barely used it anyway. I birthed vaginally with no complications.

While the studies might say it's natural for larger women to labour longer, I can't see anyone allowing that to happen unfortunately. I wish that pregnant mothers weren't judged on a few notes someone might have in front of them.