Believe it or not, this is standard electrical engineering.

The breakers in your home breaker box operate the exact same way. A 20A breaker will trip once you exceed a certain threshold, which I believe is 16 or 17. They're rated to go to 20 by the factory, but to prevent problems with overloading and causing fires/explosions/etc, they purposefully break at a lower threshold.

So this isn't just a colo price scam thing, this is the way the world works.