Why ADC's should be able to be diverse: A matter of play styles.

As everyone is probably aware, item options for the typical marksman are...well, stale. Generally the only decisions bar a few exceptions are PD vs. Statikk, and BT vs. BotRK, with virtually no deviation elsewhere (only standouts being Trinity users and Blue Ezreal.)

Say I'm playing Sivir. She has powerful spells with decent scalings and low cooldowns, and her DPS is largely affected by their use, as is her survivability (Spell Shields) and utility (Ult.) Sivir scales very well with CDR; at cap her cooldowns are 5.4(Q), 3(W), 6 (E) and 48.

Sivir's spells, particularly W, give her a large AoE presence as well. She's also rather mana hungry and goes OOM fairly quickly in any kind of sustained fight.

So, with all this in mind, I'd envision a build playing to these things about her to be optimal, right? Say something like: Trinity, Black Cleaver, Essence Reaver, another damage item (could be many things, but Bloodthirster stands out), Lucidity's and a defensive item. You get max CDR (with 5% from masteries) which effectively gives you AS thanks to your ult passive, a decent amount of AD, a mana fix so you can spam, the spellblade which synergizes with your low cooldowns and the auto-reset on W, and an AoE armor shred that all your spells apply stacks of. Sounds good?

Wrong! This is sub-optimal and bad! All that synergy and stuff? Garbage, worthless. Why? Because Statikk+IE (despite nothing on Sivir's kit benefitting from Crit), with BT and LW (because it gives a broken amount of selfish armor pent that exceeds even 5 stacks of cleaver for so cheap that, being a carry, fuck your team and get it) beats the damage output several times over thanks to retarded hyper scaling with each other (and because the mana from ER means nothing compared to the life steal from stupid right click damage that doesn't cost mana.)

This seems wrong on so many levels. Building Sivir to what should be her strengths and to work on her weaknesses being not only sub-optimal but close to straight up bad in favor of Durrherr right-click, even though she clearly has a caster-esque kit and a low 500 range, is just...stupid.