I haven't done a digital, in the box mix in almost 8 years without some type of console or tape saturation plugin. I consider them to be critical for adding vibe, character and feel to a mix. However, they only accomplish this if the recording and mix is good. They aren't going to "mix" it for you. Literally, they might add 3% to the end product. So, for people just starting out they aren't really going to help a bunch; in fact, they may hurt if set improperly.
Saturation is best done subtly. Back in days of yore engineers strove for the cleanest mixes they could get with available technology. They certainly avoided audible distortion or degradation of the signal. Saturation plugins should be conservatively employed, especially at first. Just a nip of grit and hair are all they need to contribute to the end product. Personally I load all the tracks up with the same "machine" or "console" and adjust level/drive to taste.