I wouldn't read too much into "guild." You're right that to some extent, they morphed into a small community that kept away outsiders and at least tried to monopolize some craft -- though that was in a time when many people believed in hierarchy, preordained roles, a great chain of being. With literacy at a minimum, you could only learn a craft by working in that craft.

We're moving somewhat away from credentialism -- having a PhD might not hurt, but it won't necessarily help, in many endeavors. So the informal, voluntary collaborations are somewhat like guilds seen from the inside: communities of practitioners.

I have no doubt that in medieval guilds, you'd learn pretty quick that Wulf from Sussex, despite twenty years as a master, was full of crap, while your buddy Egbert from the neighboring shire told you you could rely on that young guy Jenkin to do a bang-up job fixing your masonry.