This sounds incredibly unrealistic to me. I run web servers that get thousands and thousands of uniques a day, and they hum along fine on a single mid grade server. If you needed 10 dedicated servers for 100+ players MMOs would not be technically or financially feasible. The some of the higher traffic websites in the world typically operate on fewer than a handful of servers.
I think he meant 10 separate session of chrome (10 tabs) as host, if we're discussing in the context of C2 MP plugin.
Changing between rooms took 1-3 seconds from my tests, I think this is somehow acceptable for a player moving from a zone to another zone.
It doesn't mean it's not doable (I'm sure DuckfaceNinja has some clever tricks to share ), it means it'll be counter-productive. You still have the option of web sockets. But when talking "easy" C2 multiplayer, think "Risk of Rain", not "Realm of the Mad God", for example.
It's not a clever trick at all, but it is exactly as you said, it's counter productive. For me, I make decision to go down on that path simply because I want to reduce as much tools as possible to be able to create a multiplayer game.
Note on, creating a different project for the host, this is a very difficult to do. Imagine this, I'm capable of making a multiplayer bomberman game, fully functioning in just 2 days (with placeholder sprite of course). The amount of time I'm building/tweaking my host project, I started it in mid july, and it still ongoing now, this only involves logic and data management, I haven't even started on any visual on client. That is the direct comparison of the difficulty level, it just that much.