The medieval guild is sometimes held up as the template for an institution dedicated to maintaining high standards, and training the next generation of craftsmen.
“The European Guilds: An economic analysis” by Sheilagh Ogilvie takes a chainsaw (i.e., lots of data) to all the positive things that have been said about medieval guilds (apart from them being a money making machine for those on the inside).
Guilds manipulated markets (e.g., drove down the cost of input items they needed, and kept the prices they charged high), had little or no interest in quality, charged apprentices for what little training they received, restricted entry to their profession (based on the number of guild masters the local population could support in a manner expected by masters), and did not hesitate to use force to enforce the rules of the guild (should a member appear to threaten the livelihood of other guild members).
Guild wars is not the fiction of an online game, guilds did go to war with each other.
Given their focus on maximizing income, rather than providing customer benefits, why did guilds survive for so many centuries? Guilds paid out significant sums to influence those in power, i.e., bribes. Guilds paid annual sums for the exclusive rights to ply their trade in geographical areas; it’s all down on Vellum.
Guilds provided the bureaucracy needed to collect money from the populace, i.e., they were effectively tax collectors. Medieval rulers had a high turn-over, and most were not around long enough to establish a civil service. In later centuries, the growth of a country’s population led to the creation of government departments, that were stable enough to perform tax collecting duties more efficiently that guilds; it was the spread of governments capable of doing their own tax collecting that killed off guilds.