I think all of those organizations are great. If they make people feel better about their work then that's great. I know I have seen muzzle loading "Masterpieces" posted on this forum by "Master" members of some of these exclusive guilds that are truly horrific. If that type of work can qualify someone as a 'Master" in those guilds than I can see that they really don't mean much except to those who's egos require some sort of important title. Certain personalities demand important sounding titles, some don't. I judge all work on craftsmanship, not whether or not the builder has some guild title before their name.
Take for instance the gun you pictured in your first post. It's a nice looking gun, but it's a snap together kit by Kibler. All this guy did was do a little quick decoration on it. I have seen MANY of these kits done far better and with more imagination. The edge of the buttplate is too thick as is the end cap on the patch box cover, things a "Master" shouldn't tolerate. the engraving is nice, but there are many people on this forum that do far better work than that, and they aren't referred to as "Masters". The "Beautiful finish" isn't any better or worse than what most guys on this forum are capable of.
So, I'm now wondering, why did you chose this particular fellow and gun to make a post on?