The artisan guilds were immensely useful in the Renaissance, when trades tended to concentrate in one town, like books, in Frankfurt, or metalwork, in Nuremburg. There were usually a number of reasons for that concentration. But a big part of it was the difficulty of transportation and the need to pool talents and supplies, to have them available. But that concentrated market meant that there was a real danger of competition driving down profits until everyone in the trade was starving. The guild kept that competition under control, and as well constrained a danger of such competition, that artisans would be tempted to compete with shoddy goods, that were cheaper.

However, as trade increased, skills and craft knowledge could disperse, and the urban guilds had less and less control. David S. Landes did a nice outline of an example of that in the pocket watch trade. Efforts by a guild to regulate competition within Paris were pointless, if watchmakers could set up in Geneva where it was cheaper, and membership in the Geneva guild was not going to prevent watchmakers from setting up in nearby Jura, where it was cheaper still. Membership in the Gunmakers' Guild in London was not really necessary if a journeyman gunsmith was willing to work in Birmingham. And, of course, by the 18th c., increasingly no one had to travel to Paris to get a watch or London to get a gun- they could order one, and salesmen could travel to foreign markets with watches for sale, from either Geneva or the Jura. While a market was fixed and local, a guild was a handy thing. But when markets could spread and trades could cross borders, guilds could not really be effective.

Landes, David S. ( 1983) Revolution in Time: Clocks and the Making of the Modern World. Harvard University Press.