Thanks to both of you ! I now understand where those hundreds of people were located : shame on me for not using my Canadian PhD brain to figure that one out ! (I do not have a lot of online MP experience, obviously).
My main problem, then, is this :
Suppose I do not want to host a game, but only join a game suitable for MP « n00bs » such as I. How do I proceed to find a game where I won't get matched-up with MP vets ?
Yesterday, the few available games to join did not seem to give out any sort of info on the skill-level of the host's ideal target-audience. Of course, I could have asked the host in his game-setup area, but it would be less bothersome if some game-ID option could explicitly advertise the required skill-level for an offered game : less loss of time and less chances of unfair match-ups.
At the moment, I'm a 57-year old MP-n00b who does not want to be bullied by 12-year old MP-Veterans.