drink the amount that works for you.
I used to habitually bring (and drink) two 24oz bottles on every ride, regardless of length. I noticed as I lost weight (and got fitter) that I was less thirsty. So much so that I sport just one bottle cage these days. My regular weekday rides (20-30mi) are with one 20oz
bidon (
tel que https://ellumbagworks.com/product/fundamental-bidon/) --about half of your 1 liter/30 km recommendation. Now that it's really hot (finally), I'll actually drink the whole thing and perhaps refill mid-ride. Rode an organized century at the beginning of the month, topping off at each aid station. Probably totaled 4-5 bottles for the 103 miles (~3 liters for the 165km). --Now during that same 103 miles I also went through 9 Hammer Endurolyte pills.
What you see as "controversy" can also be interpreted as "varies by individual."
This is one of those "do it because you feel good" things, not "do it because the internet said so" things.