Originally, the water was the critical component. Hard water, and light-colored lagers come out the best, soft water, brown ales. Add to that fermentation temps (climate) and how the grain grows in your region, and you get regional beers.
Today we can engineer the water and select components, but if you are an established brewery you’ll continue to brew what your customers want. So if you start making light lagers without much flavor that must be cold to be enjoyable, that’s what you brew today.
Brewing something like Bud or Miller is not easy to do. You can’t hide a mistake behind a dark color or strong flavor (so batch-to-batch consistency is tough as input materials change), and chill haze is always a problem.
Precisely correct.
The American Light Lager (not lite) is the most difficult of all beers to produce.
It's the pinnacle of brewery science.