Yes the fact that players can create an economy makes it a game mechanic. A Merchant/Store Keeper/Trader/ect have always been in the game. Because there may not be a player taking the role, they made NPCs.
Players made the non NPC economy what it is. And the devs have no problem feeding it.
Maybe it is more advanced that RG thought it would become. Seems more advanced than you accept.
"Advanced" for sure, and in a very peculiar way!
From RG interviews, there were 3 main points that were the central focus of UO from the beginning: Dungeoning, Economy & Ecology (a food chain, ect).
The third one was TOTALLY WASTED by players on a "kill-all-that-moves" spree even in the beta (see the
famous RG interview on this...
![Stick Out Tongue :p :p](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
), and so was quickly down-scaled to what we have today: "spontaneous generation" of various critters from the Sosaria soil itself.
The first one has stayed more or less the same from 1998 till today, even considering the various Devs' teams (not only by the current one) "nerf-all-that-kills" sprees, and even today lives its own life, with the Virtues, the narratively and graphically elaborate quests (that falls well beyond the capacity of 90% not only of UO players, but of 90% of today human beings at large, to be undestood, let figure appreciated. But, hey, Writers gotta write, it his their Nature
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
) .
The second... well, it gots its downfall (or lateral-fall, if you prefer) incorporated in its nature itself, with its Auction Safes & Vendors filled houses (and a sooo American one!
![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
I apologize for my "discrimination", but that it is the reality: remeber
what was written about Romero & the meaning of choosing a Mall, a Temple of detail consumerism, as the setting for the seminal "Day of the Dead") .
A couple of times (before the today age of "shop by Home" made possible by the Global Vendor Search... I find SO FUNNY that now we have a REMOTE SHOPPING SYSTEM in a MMORPG like we have Amazon in the real one...
![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
) I imagined the Avatar and his Companions on a rampage in Luna (that should have been the City of the Paldins, but has become a den of... well, thieves and scammers and money-lenders too, at least!
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
), chasing the Vendors outside its walls, but that CAN NOT HAPPENS, because the Vending Contracts were and are issued by the Avatar original creator, and woven in the "fabric" of his silver-plated, ankh-marked chainmail itself...