I used to trot that out for carbon too. But its MTB frames. They are built heavier and stronger to withstand more.

Let's see the same tests done with CF road racing frames. The result would not be the same. We all know it.

Like Maelochs was saying, you just have to decide what your design priorities are. For me, better ride quality and durability win out over shaving a couple of pounds (the weight of a full water bottle) that only helps in a 10+% climb. So I choose steel.

If I want my steel bike to weigh the same as someone else's CF bike, I just leave a water bottle at home