With all due respect you probably do not work in an institution where you have to rely on SAML for day-to-day operations (I work in a uni, so Shibboleth). If you did, you would realize why SAML is lauded as a great solution, but in reality can be very fragile and needs to be rolled out all or nothing. I have been part of a multi-year piecemeal deployment and it has rough edges.