I did this, and it was great at first. Then I needed more socks, so I bought another batch. Then I had a mix of worn socks and brand new socks. They might look the same at first, but if you take a closer look, the older ones are a little lighter in color and the texture isn’t the same. I later bought a third batch. So now I have a mix of new, old, and really old socks. It actually takes more effort to match socks now than when I had many different socks.
I see this advice posted all the time, so I guess most people don’t care if their socks on each foot are a different level of worn, but it bothers me.