Not at all. I worked in video production and deadcat's only really have one function and that is to act as a wind shield without affecting the acoustic pick-up of the microphone (i.e.: you don't get that "muffled" sound).
The are normally used outdoors or where fans/air blowers are present.
If you're filming indoors, even in an air conditioned environment, wind screens are hardly ever required.
Pop filters however are very useful in voice-over recording.
But yes, it's true, a good cat is a dead cat.