I have to agree.. it's a way for MA to keep the items within the system without adding any new ones.
You should update your OP to specify if you mean TT loot-pool in financial terms or if you are merely referring to the items/resource loot-pool which is managed by the system to both keep the economy flowing and manage a balance between what is available to the playerbase item wise and when (Both UnL & L dropped items)
If TT in terms of finance then no, a common shared loot-pool "for all decay" does not exist as it suggests gambling - ie. sharing of your own funds with others in the form of a lottery is gambling by definition.
Personal TT lootpool yes, this is simply the accounting core buffering (accounting) for funds stored to be returned in the form of markupable loot depending on whatever criteria you have contributed to the flow within the economy. (Possible examples: Taxed land, markup paided out, yadda)
Loot pool in terms of items and resources is the BASE departments area for maintaining a balance of a healthy and competitive economy as to distribution and uptake (use/decay).
As you can see in terms of assessing gambling, the OP is very vague when referencing to loot-pool in general.
Any gifts I would refer to as spanners in the works, yes they do occur - eg. Newbie HoF/ATHs
Additional money added to the system from Massive Corp advertising, short term investment portfolio earnings (token profit distribution) would either be handled by the accounting core based on per-capita participation in one form or another (Possible examples: TT spend, time online, yadda) or be allocated out "occassionally" (so as not to be defined as a lottery) as gifts as mentioned above or a combination of both these two mechanisms.
There is also the "potential" of mechanisms such as this:
LINK >
Another potential distribution mechanism
Which would be classified as a re-distribution of part of MindArk/Partner revenue back into the virtual world environment as gifts.
This would be a very tiny amount of the calculated return % taken and if it does exist would explain the existence of "hot" activities (Hot mobs, hot items to craft, yadd at any point in time).
It is also where the trackers are able to make statistical based predictions on what activities are "potentially" returning well based on trend analysis - Overall focus from participants within a recent past timeframe.
Those who are non-depositors and are consistent with their activities would ride such a mechanism (playing smart) to continue their activity as non-depositors.
Leeloo also has a thread response from MA which provides partial insight into the system.
LINK >
LOOT
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