I assume it also depends what we carry. I have a laptop + accessories, a whole set of clothes and shoes to change, tools and a spare inner tube so that i can fix my bike on the road.
In addition I sometimes stop on the way to or from the office at a grocery store to get some food or drinks. And I am having back problems and I don't want all that weight on my back.
Therefore a backpack is a no go for me. But this is me. I have a set of Ortlieb backrollers which I bought over 20 years ago and which I still love.
My son however only uses a backpack when riding to school. But he has a lot less to carry.