I would say not that many people are putting their autos in 7gals. Like stated above 3 gal probably the average grower pot size.
Also feel like they're probably not trying to get into the business of saying what the maximum potential is because who knows what the odds of hitting that actually are?
If one out of every 500 grown can hit that max potential is that worth telling people about it?
I don't think the likelihood would be that low. I've seen so many now it's starting to look easy.
Also unless a genetic is pre-conditioned by breeding to favor a small pot, most plants max yield would be limited by pot size, up to a certain point. Not sure what that point is for Autos but I'm guess it can't be above 15gal.