I wish it wasn't but it is unfortunately accurate.

This isn't caused by a lack of sufficient power, it is a more active restraint caused by the Dell checking electronically if the power adapter is one of theirs or not.

I've had the problem myself and had the debate with our Dell account manager.

It only affects more recent models like the XPS M1330 for example and it doesn't stop you powering the notebook, it just very effectively stops you charging the battery.

I won't be surprised if a 3rd party manufacturer comes up with a solution sometime soon though.