Admin Shop Opinion

This is my opinion in how server/admin shops, which is not necessarily definitiely correct, but that seems most correct to me. Some of my points aren't really developed, it meanders a bit, and perhaps the tone is harsher than intended. That said, here it is:

Allowing server shops for common blocks like cobblestone, dirt, sand, wood, and netherrack is perfectly fine in my opinion, as it helps to stabilize the economy from swinging too wildly and to limit inflation. As long as the buy:sell ratio for these items is fairly large (preferable at least 2:1), this will encourage players to trade these items with each other in precedence to using the shop, while still allowing the shop to be used if a trading partner cannot be found or a price not agreed upon, thereby boosting the player economy rather than stifling it.

A server store many other items seems fairly problematic to me however, especially ones that are otherwise in quite limited supply, such as diamonds, or just a wide variety of items in general that otherwise would have to be obtained though normal gameplay. The way I foresee such a system playing out seems to me to impair the economy that the system is designed to promote in the first place.

By fixing all the prices, so they are limited to a small range and can't rise or fall past that due to supply and demand, the economy is made static and prone to breakage if the actual supplies or demands of items don't match the prices set by the shop ahead of time. If, for example, there is more iron in the economy relative to coal than the shop prices predict, this will incentivize players to convert iron to coal via the shop, rather than to find a use for the iron, use less coal (preferring charcoal or lava perhaps), or seek out more coal as would happen in a vanilla minecraft economy.

Additionally, if the price that supply and demand would set is outside of the buy-sell range at the server shop, players will always choose to trade with the store instead of each other, drastically limiting the ability for player-run shops and the like to work. Even if there are some players offering to buy or sell items at prices within the range, the existence of the server shop for most items in the game means that many players will choose to simply buy or sell at it rather than seeking out a player or player shop to trade with. If the buy and sell prices at the server shop are identical, this becomes even worse, as players will never have an economic incentive to trade with each other, entirely breaking the prospect of a player-driven economy for these items.

Aside from these, perhaps the most prominent issue with server shops as planned is that makes things overly easy by allowing items to universally be converted to other items. For instance, this allows all players to gain more diamonds than they could in vanilla by trading in other items such as redstone they need less of, and simply buying these items back should they find a need for them later, which not all players will. In a vanilla economy, the number of diamonds overall would be constrained to the amount mined, found in dungeons, or otherwise obtained through normal gameplay, requiring players to conserve their resources more, or obtain more either through gameplay or be buying them from other players.

Another manifestation of this is the fact that a server shop would allow every player to require only one farm or mine or whatever else, whichever turns out to be the most profitable, and obtaining other resources by selling the items from this farm/mine to the server store and buying the other items with this money. Without a server store, [supply and demand would cause the price of widely farmed items to fall until they're no longer very profitable] all sorts of farms, mines, and other means of obtaining items in game need to exist, even if distributed amongst various players, requiring the server population to diversify their means of production. By allowing players to easily buy any type of item from the store, the importance and achievement of obtaining a large quantity of a rare item or building a creative farm to produce it is greatly diminished.

The key factor as to which blocks or items work in a server store, I think, is that are are easily obtained in such large quantities that buying or selling them won't disrupt the in-game acquisition of them. This is true for cobblestone and dirt, for instance, which players can easily mine dozens of stacks of and many do over the course of normal gameplay. It is most definitely not applicable to diamonds however, for which finding a single vein often makes a significant difference, and introducing to the game a supply of them that is limited only by the amount of currency a player is willing to put into it breaks both the value of diamonds that makes players more willing to buy or sell them amongst themselves, and the aspect of gameplay revolving around searching them (and other ores) out through mining or caving. This doesn't only exclude the rarest items, however, but the opposite - essentially every item but the most basic should be left to normal gameplay to be obtained, which includes everything from cactus to obsidian to red sand to sticky pistons.