This is not entirely true. This is the maximum number of spaces that can be configured in the OS Settings > Keyboard > Shortcuts, is 16 and if you only have one screen, that is the max you can create, too.
I currently have 21 spaces active because I originally configured them with an external monitor, and when I unplugged the monitor, nearly all of them were available on my laptop. The exception is that all windows on the first screen of the monitor get moved to the first screen of the laptop and what had been the first monitor screen is now unavailable. On the laptop alone, I cannot add any more spaces. If I plug in my external monitor, then I can add spaces, my guess is up to 16 per screen, I haven't tested it because I haven't needed it. I predict that if I then unplug the monitor, I'll have 31 spaces on my laptop. One of these days, I'll try it.
The best tool I've found for managing spaces has been the free app Current Key Stats, but it is no longer available due to the developer becoming a father and not wanting to port the system to the latest versions of the OS. Just too much work for a free app. He made it work by creating an invisible app on each screen and then getting the OS to switch screens by making the appropriate app window active.
Because he's no longer supporting it, (a few months ago he was putting it up on the app store for one day at a time, on request via Twitter), I would love for him to put it on GitHub or for someone (e.g., @peternlewis) to buy the rights to it and integrate it with some supported product (e.g., Keyboard Maestro). But that's just a dream right now.