Is there any reason to buy Mejai's Soulstealer?

I find many players that rush this item for champions like and and sometimes even . I actually like to laugh at Kat players that rush this item and then go 0/9.

However, is that item really worth? Because I feel that unless you are using an AP mid laner with really high AP ratios and is snowballing hard, there isn't any reason to buy this item, and even then, at late game it is way better to sell this item and replace it with other, better AP items.

This is because not only you are required to not die to mantain stacks, but also even with full 20 stacks, the benefits that this item provides pale in comparison to what other AP items offer, and you aren't even required to not die when purchasing them.

At full stacks, this item offers 180 AP and 15% cooldown reduction.

The 15% cooldown reduction is not worth when I can just buy an item like Morellonomicon or Athene's Unholy Grail and achieve 20% cooldown reduction, which is superior, not to mention the mana regeneration. And even for Katarina, a champion that commonly purchases this item and does not use mana, well... Thanks to her passive, she doesn't have to itemize for cooldown reduction at all.

180 AP is indeed an high amount, but unlike Rabadon's Deathcap, it does not multiply other AP items that I have. Rabadon itself offers 162 AP. This is less than 180, but at least Rabadon multiply other sources of AP that I have. With just 16 AP, Rabadon already surpasses the AP that a fully stacked Mejai offers. This means that assuming that I am not using AP runes, masteries, and that I don't have other bonuses, if I were to start the game with a Doran's Ring then rush a Rabadon, I would have AP equivalent to a fully-stacked Mejai. Even though Rabadon's Deathcap is almost two times the price of a Mejai, it is still very gold efficient as a first item purchase, and although it is not slot-efficient early, this item becomes slot efficient as the game goes on and you stack more and more AP.

Not to mention, a fully stacked Mejai does not offer anything that I would want that I can have with other AP items, for example... It doesn't matter that I have a lot of raw AP if enemies are stacking magic resistance and I do not have a Void Staff to counter that. Mejai also doesn't offer the survivability of Zhonya's, extra burst from Luden's Echo, anti-HP stacking power from Liandry's Torment, and so on.

So I wonder why so many players like to rush Mejai's Soustealer when this item is a complete gamble, most of time you do not have any assurance that it will work, and even if you manage to get fed, if the game somehow goes on and the late game comes, I see myself being forced to sell a fully stacked Mejai to purchase items that would better fit my needs.

In other words, unless you become extremely fed and end the game before the 30 minute mark, then you are just wasting gold, gold that you could invest on items that would be far more efficient. Usually when I see an enemy purchasing Mejai when I am winning lane against them, I see that as a challenge. It is like they are saying "Hey, I will become fed, I will carry this game, and there is nothing that you can do, MWAHAHAHAHA".