Relying on Diana's autoattack passive is silly. She needs to get into melee range so unless you are trading with a melee champ you are unlikely to get more then 3 autoattacks off on an enemy so only one passive proc. It's much more efficient to get more AP on Diana then attack speed and Luden's is a very good choice for the increased move speed which Diana needs to smash orbs onto people and refresh shield.
Nashor is much better on autoattack reliant champs like Kayle or Rengar who can get more autoattacks off.
Renger. Nashor's on Rengar. The same Rango who only has one AP scaling versus two high AD scalings. The same Ragoo who has a massive AS steroid on his primary damage ability. The same Ringuini who gets all the AS he needs from Youmuu's active. Would you also suggest Nashor's on Vayne?
Sorry, I can't take anything you said seriously. Especially when it came at the tail end of a bunch of people explaining why Nashor's is in fact a good buy on Diana.
Mind, if you're playing high-end Ranked 5s with your team on comms, you could probably forgo it most games. But going for 100% initial burst 0% utility for a champion that can't 100-0 anything but a 30-MR carry without being fed when you're playing alone? Trusting that your random teammates will reliably be able to finish fights and close out matches after you maybe kill one person is not a good idea.
There's an enormous difference between needing 1 Q and three autoattacks and tossing out a Q and killing the casters. You need something on the order of 350 AP to be able to kill casters with 1 Q by the time you can reasonably have that amount. Ludens lets you do it pretty much at level 9. Deathcap puts it off for another item or two.
Why do you need to be able to do that by the time you have your second item? The only situation where early fast waveclear is useful is if the enemy naturally pushes lanes. Unless you're incompetent enough that you can't farm under turret, that doesn't matter. If the enemy laner wants to keep shoving under turret, let them, and call your jungler -- even if they're a tool and ignore you, it still gives you a favorable position in what is apparently a tough lane, making it harder for the enemy jungler to gank and providing more space for you to fight and chase if the enemy laner does something stupid and you get onto them.
Diana's a lot like Akali in terms of early laning, really: you just need to learn how to farm under tower and live until 6, then focus on getting kills. It doesn't matter if your waveclear sucks early and can actually be beneficial if the enemy laner stays in the habit of AFK pushing after you hit 6.
Also, your numbers are bullshit. If you get every drop of lane experience (unlikely, so we'll assume that missed exp balances out with potential kill involvement/leaching off Raptors like a scumbag), you'll hit level 9 at 10:30 in game. With
perfect CS (fat chance from even relatively good players, much less Plat/Gold/Silver/Bronze) you'd barely have enough gold to get Deathcap.
So unless you're magically teleporting around the map getting participation in a bunch of kills, stealing jungle camps, and
still getting perfect CS in lane, you're not going to have that. Luden's you can get
if you have near-perfect CS (still unlikely). And then you're stuck with a poke tool designed for champions like Nidalee and Vel'Koz that does both jobs poorly instead of one well. It's like a Lich Bane, except it can't hit towers and will probably only proc once in a fight. It's like Nashor's except it forces you to burn MP to waveclear. It's like Deathcap except it doesn't scale as well and isn't gold-efficient even with the passive, never mind without it.