Maybe other summoners didn't use the same way to get to the Chamber of the Fayth - after all, you're on the run when you get there, so it may be that the party has to take a non conventional way to do so

Sometimes also, when the faith is very strong, some may stop questionning what is done in the name of the belief system they support. Using machinas wasn't the only oddity during a typical summoner pilgrimage, yet some go through with it, or even go to great lengths to defend it (think Isaru....)