Why zephyr was removed?

Before to start this post is just a bunch of question about why zephyr should't be removed. I'm not good at cost efficiency or serching old post so I don't know the real reason for why it was removed but I almost figure all the question relative to this item and explain why they shouldn't. Let me know if you know the real reason and if i'm wrong.

After play a bunch of nexus blitz, I miss this item a lot on SR (i play from the start of season 4). This item was really good on almost all adc and other Aa user. It provide tenacity without give real tankyness so mages and ADs was still able to burst their target but at least them was able to avoid the Cc stack. Since Berseker's greaves provide only atk speed and movespeed, most adc always sell the boots to grab zephyr since it provide a good ms. So I just want to know.

Why zephyr has been removed?

Because it was never builded? I always saw people buy this item at least as last item.

Because it was too powerful to balance like banner? Mercury's Treads shared the same unique passive and it was at 1200g and now at 1100g. Zephyr gave a small amount of real damage (25ad if I wasn't wrong) and a bunch of atk speed and movespeed (it was basically a true adc item)

Lowering Cc chain was a problem? Honestly yes it was but as I alredy say merc boots has less cost so every champ could use it and Qss was way more powerful. Nowadays Cc is like a death sentence (1 is enough) and tenacity doesn't work on displacement so it's not even near to op. Also having no armor/mr/hp this item couldn't save from a lux combo, but would give to player more reaction time.

Selling boots to get another damage item was an issue from game design? No. People are still selling boots to get another damage item. I always sell boots to get double zeal or double lifesteal or even lifesteal and armor/mr item on adc (as last item). In the past, adc's even when they removed zephyr, they still sell boots. Zephyr wasn't not even close to almost buy this item but it was still bought if required.

Zephyr was too powerful as a kite item? Well zeal upgrade do the same as zephyr do but they provide more thing. Melee has alredy a bounch of ms effect that wasn't present in the past. Even volibear can run toward an adc with a bounch of ms active to pull and kill him. In the past melee was always kited as hell but as I alredy say adc could just grab a double phantom dancer (season 4 phantom) or double zeal item and still kite as hell the melee so it wasn't a problem. So it was a real good sustained dmg item, it wasn't a true defensive item but it still give a little bit of help (also this would help a lot adc with fiddlesticks without nefating his dmg).

Thanks for reading this bunch of question.