The problem is that additional false information is worse than no information, and without already having a detailed knowledge of how things work in full, it's impossible to provide correct information. In order to make a proper Civiliopedia update, you have to already know how something was designed, and that's the kind of knowledge that you only have if you built it.
For some things this is true. But take the mithril golem example; you don't need to have the kind of knowledge you only have if you built the mod to know the armageddon counter needs to be 70 to build the thing, you only have to have been around for a long time since apparently it used to be in the civilopedia but was accidently removed. According to previous posts on this forum at least.