Well yeah, that is true. It helps to know so you can buy the stuff you need rather than running around like a headless...
I would let the hormones do the talking, mine was like that, didn't want to know but when it came to it, she wanted to know what we were expecting.
It does make life easier to know, loads easier on the pocket too.
It does not matter what weight they come out at either as that is not any indication of growth rate, I can testify to that with my own son. he popped out at 7lb 3oz. He is 2 years 4 months old. He is just above the 98th centile when 50th is the norm. He has the build to go with his tall frame. In simple terms, people mistake him for a 4 ~ 5 year old, he takes clothing that a 4 year old would wear and even now, clothes tend to only last a few months.
So holding off in spending too much on clothing is a good bit of advice.