Feel free to PM me with any specific questions you may have, conceptual or in practice if you have an example you are working on.
The official multiplayer tutorials are excellent and features tons of very concise information. They go into "what is best" and "why" on top of "how", in addition to giving you the background necessary to understand the "why" as well. Unfortunately this much information may discourage newcomers just looking for the "how". For me, it was great since I love reading and understanding the "why" behind the "how".
A more easily accessible tutorial might start with just the basic goal of multiplayer - how to send data from one device to another. Leave the "What should you send, why, and by what method" for another tutorial, or in this case, the official ones. This also describes what you should use the plugin for.
Honestly though, anyone skipping out on understanding all of the concepts behind multiplayer is in for a very very rough time dealing with all the nuances of bandwidth and time-delayed communication and its implications.
As for users - it has been mentioned a few times that the multiplayer plugin gets very little utilization. I think most people are not able or do not realize what it takes to design multiplayer integration, and get discouraged when all the information is presented. Besides understanding how to use the plugin is actually making a game! I wouldn't be surprised if a very small population of users have completed games, regardless of multiplayer. For example in my case - just because I have a very clear picture of the plugin's capabilities and how to put it into practice doesn't mean I can put together a good multiplayer game!