The power acquired through items is quantized at the moment of purchase-- you do not continuously access the power over time. In other words, you have all of the power "at once". Even items like ROA which try to deliver power over time only deliver it in a finite number of chunks rather than continuously.
This is important because the larger the chunk the more gold must be expended to access the power of that item. A large chunk requires holding onto gold for a longer period of time, making you weaker than an opponent who spends their gold immediately.
The only significant reason for any high tier item to not have component items and instead have very expensive basic items is to discourage building them early. Component items are invariably composed of cheap basic items like tome and longsword, making them more practical to build earlier in the game where any amount of swing in power no matter how small could play a significant factor in the evolution of the game.
Infinity edge is composed of large items to intentionally make it impractical to rush. Blade of the ruined king is composed of many small items to intentionally make it easy to rush.
The question should then be "Should this item be rushed or not rushed? Should I discourage players from rushing it for gameplay or balance reasons?". For atmas impaler, which becomes significantly stronger as your champion levels increase, It is prudent to wait until you have acquired many levels and gear before building it. This suggests that atmas should consist of large hard to build items, like chain vest and agility cloak.
The avarice blade is worth special mention because it is an item that is easy to build but allows you to trade inventory space for what is as near to a "continuous" flow of power as the game can provide, a steady increase in gold income over time. Naturally holding that item for longer means accessing more power later. The problem is that difficult to build items composed of large basic items like infinity edge already do this-- you already get more power than an easier to build item or there would hardly be a reason to build them at all.
The real functional intent of avarice blade in an item like atmas impaler is to provide you with the choice to give the atmas' impaler a virtual increase in power (reduced cost) by trading an item slot during a significant portion of the game. That in itself, the power of being able to make a choice-- having an option rather than not having any option, is a sort of higher level power, a strategic power.
Most players do not consider their choices this deeply though, and most players do not consciously trade power now for power later with their itemization choices. The last time this was actively done by the player base Heart of Gold was removed from the game because it stagnated the game and removed interaction for the greater portion of the game, since the defacto norm was for everyone to trade power for later. That item had its own issues that allowed that to happen, specifically it granted regeneration that removed the risk involved with making the trade "power later for power now". Avarice blade does not do this.
In any case I can see the value of having avarice blade in the recipe for an item, but unfortunately the choice is artificial. Even if you do not want to trade the power in the way described you are forced to because it is a part of the item's build path, and unless you wish to simply build the avarice blade as part of the item recipe so that it does not occupy an item slot for any time at all, you will build it at some point. If the item had multiple build paths this would not be an issue, but it would complicate the game.
I do not assign significant gameplay to avarice blade and in my opinion atmas should have larger more expensive basic tier item components that are difficult to build, in order to encourage people to build other items and delay building atmas until acquiring gear and levels, which is when it will be stronger.
