Here's an analogy ...
Some (Windows) computers have a power outlet on the back. The intention is/was that you could plug your monitor into that, and save having to use up two power points on your desk.
Now you might be tempted to think: "ah, power!" and hook up your toaster, room heater, or electric drill to it.
But that exceeds what it is designed for, and the intention of such outlets is not to be a general "power supply".
So, it may work (powering the servos from the Arduino). It may work reliably. But quite possibly not.