I suppose so... although it doesn't give perfect results on blurry id passes. Also, either you have to invert the alpha to get a trackmatte (?) or you have to key out every color but the one you want. But it does the job. I've also just had a bit of success using the Change Color effect and then selecting the view > color correction mask instead of the color corrected layer. That seems to have a bit more flexibility with the tolerance?