Why you may ask?
They can poke you safely for days, they usually have escapes of their own.
There are many more issues but the one that is the worst offender is that *They bully you harder than some melee bullies and scale even harder than you*.
Frankly this is some bullshit, I can play Darius top but the moment the enemy picks a Vlad, Vayne(yes she's being abused top now), Lissandra, Gnar, and many more, it doesn't matter if I shit on them in lane or lose to them in lane, **they will still scale better despite being able to bully me harder than a Renekton and safely**.
Why pick a melee champ that scales worse when you can pick a ranged that scales better AND bullies harder?
Edit: I see the discussion here and most of you seem to have the idea I'm talking about only Darius having trouble and that he should.
I'm not saying ranged should be nerfed to the point of him being able to shit on them nor am I talking about just Darius being in the shitter vs ranged, look at Garen, Volibear, Gangplank, and Olaf as well.