The skill system in 5e is one that favors "oh I'm profuicient.. me too.. yea ,e as well can I roll too?" over the kind of narrower specialization where the party needed to individually use their strengths to cover each other's weaknesses. Multiple players take a & S tier skills simply because it's trivial to do so even if basketweaving & some B grade skills are a better fit for their classSure. I'm not saying that mechanically that's the best way to represent it. I'm saying that the wizard is an educated class and that's just one more, very blatant piece of the wizard class that shows it.
Also, if there is a rogue taking arcana, and there's a wizard it's stupid for the rogue to take expertise in arcana if the wizard is going to. Better to spread out the skills in the group that have expertise attached to them than to step on toes. Just like it's not that smart for a wizard to waste a spell pick, memorization slot, and active spell slots on knock when you have a rogue that can just open virtually any door anyway given a few minutes.
Classes can step on toes, but it's counterproductive to do so.