Reading Steven Pinker's Blank Slate again and revisited the concept of Universal Grammar (first proposed by Noam Chomsky)- the posited common underlying rules/infrastructure on which all the world's various languages are built. The theory is that we all have an innate instinct (a language instinct) for these rules and that, based on which specific language we are exposed to as children, various switches are thrown (determined by the environment in which we are raised) that determine the actual manifestation of those rules (e.g. which language we speak as adults). Its asserted that that is why learning a language as an adult is so much more difficult that as a child, you're fighting against the switches that were set long ago.
Universal Grammar suggests that the underlying structures of language, the grammar, is innate and the same for all humans; different languages are the result of some config file in the head of a young child being set with various binary parameters. The simplest illustration of one of these params is the choice of Head first or Head last; depending on which choice is made, a language is either SOV (Subject Object Verb) or SVO (Subject Verb Object) with many associated orderings in other aspects of syntax. For instance, Japanese is a SOV language and English is typically SVO. In Japanese, the verb always appears at the end of clauses and sentences (a fact which makes my sometimes attempts to learn the rudiments of Nihongo interesting).
Given the recently introduced concept of an identity 'metaystem', the idea of some set of fundamental set of rules and/or components, from which various identity applications can build, seems appropo. Just as languages differ in their particular manifestation of the Universal Grammer, particular identity systems will inevitably vary in their manifestation of the basic underlying components and principles.
I can imagine that in the 'mind' of every young SSO architecture, there is a config file with switches for 'front-channel vs back-channel', 'remote or local storage', '3rd party or self assertions', etc. The specifics of the environment in which that architecture (e.g. B2B, constrained client, privacy requirements, legislative issues) grows to maturity determine how the various parameters are set, and consequently the use cases for which that architecture is appropriate as an 'adult'.
So I guess we shouldn't feel bad about favouring one federated identity architecture over another - it's just that we are adults and our switches were set long ago.