Not a silly question, Anthony, a very pertinent one. I would suggest it is more revealing of my own lack of knowledge of networking stuff actually. Never considered using LDAP, or SAML. First, do all those Apps allows the use of LDAP? I don't know, I know Moodle does and the Network guys are always complaining that they actually can't get it to work with the logon protocols or login authenticators whatever they use. (The only one I have heard mentioned by name is IChain, and I am not sure that is even how it is spelt, and I have no idea how it is done in the Moodles I am an admin for now.)
This sort of thing seems to move into realms of networking that most of the people I have worked with do not ordinarily use, do not really understand. I suspect that this is a structural thing that my employers are going to have to make a decision about soon though.
Here it is, my employers decided to use Moodle, at the encouragement of a prominent member of the Oz Moodle community, and good for him. His company provide the Moodles, the servers and everything else, at a cost I assume, and we access them. Each school in the State, (which is nearly twice the size of Texas and about 1/20th the population,) has one Moodle, which makes about 400 odd Moodles, not all of which are being used - and few are being used extensively.
My argument is that Moodle on its own fills a purpose, but it is not all things, and we should not make it all things. We need to use other PHP Apps, which need to be on the same server as our Moodles, and thusly we need a single login to access all of them. I doubt that LDAP will meet that need, as the Moodles are not on the same servers as each school. In short, it is a bit of a nightmare, but it is getting to the point where others are recognising that Moodle on its own is going to be insufficient to meet all our needs. We need Mahara, we need Mediawiki, and I would suggest we also need WordPress. I have all these set up on my private server and I do not understand enough about PHP to develop my own single login. But we need it - if not right now, then in a year or two.
I am also quite sceptical about the longer term economic health of the world, so delivering cheaper school support services that will last for many years without replacing the computers, the servers or the software, is going to be a high priority. As licensing will become a thing of the past, as most of the existing companies will disappear, even Microsoft and Adobe, and Apple, and be replaced with who knows, we will need to depend on Open Source, and have people who can run fixits, make patches and so on, just to keep things going - but that is another story.