Panasonic NJS

many people are comfortable on their bikes, but a fit takes in other considerations such as power output, frame geometry, optmising performance, injury prevention.
so comfort is not the only factor

This. Many people have, or spend a lot of time and effort to make a bike that is comfortable when they get on it but then they piss and moan about a sore back when they have been riding for only an hour or two, blaming themselves for being too stiff or unfit when in reality, it's the bike fit that is wrong.