Well, yes, at least for pet rabbits that's the most common advice. For good reasons.
But compared to pellets hay adds a lot of work, and good pellets will work fine for the time rabbits are productive in a meat raising szenario, and of course there are no long term health worries with growouts.
There are many ways to feed rabbits properly, not just one (no matter how often it'S repeated all over the net). Whatever works for someone is fine. Rabbits aren't rocket science, when I was a kid they just were an affordable and easy way to get protein on the table.
I feed forage whenever available, hay when not, fruit, vegetables (Pumpkin, Topinambur), trees - whatever - because I dont have many rabbits and gathering stuff is part of the hobby for me. I use pellets just as treat and supplement. This is not the most effective way to grow meat, I usually butcher at 5-6 months.
As for how often I feed, i gather forage in the evening, they get one batch right away and the other in the morning. In winter they always have hay, get veggies twice per day, and pellets only in the evening as reward for going back into their hutches. Water isn't so much of an issue for me here, I clean their crocks once a week and just keep them topped off otherwise, and half of the day they can go to the creek anyway. It seems I'm quite fortunate with the local climate though, never had any problems with Cocci or so.