The conventional wisdom was always to carry weight low and closer to the centre of mass, thus low rider panniers and using rear panniers rather than just stacking things atop the rear rack.
Large handlebar bags suspended from the handlebars can make the steering very unstable. Now I see people with all kinds of crap lashed to the handlebars and I wonder how the bike handles.
People used to say “Load your bike not your back”, but that adage seems to be gone now.
One of the major advantages of a bike packing set up is it forces you to pack lighter
and carry less stuff. You just have to make sure your safety and comfort aren’t compromised.