No one should tell you what you ‘must’ do. You’re free to use whatever method you want.
I use BBF because I came late to autofocus cameras and was frustrated by using the shutter button to activate AF. My brain automatically thinks of focussing and picture taking as 2 separate functions, and I’m more comfortable keeping them that way.
The advantage for me is that I can leave my camera on continuous AF, and I can use the focus button to achieve focus, then recompose and take the image at my leisure. It’s easier than holding the shutter half way, switching off AF etc.
Nowadays I have a more customised version of this where I use single point AF on one back button, and eye tracking on another, so static objects, focus recompose, track objects by keeping my thumb on the button, or track people with my thumb on the other button. All without changing a thing.
I ‘can’ easily change AF modes simply if needed, but I generally have no need.