In the post about the steamer you said, "The warm steam will help open up your hair's cuticle which will allow your hair to receive all the beneficial ingredients found in the conditioner." Is this the same thing that occurs when you sit under the hair dryer? Is one method more effective than the other?
The dry heat from a hair dryer, the heat from your head - coupled with the moisture contained in a plastic cap, when used with conditioner, will create an environment similar to a hair steamer since the goal is to create a warm, moist environment to help open up the cuticles and receive the benefits from the conditioner being used. When using a hair steamer, a plastic cap is not needed; you simply fill the steamer up with water and sit under it. With the steamer, you are getting direct and constant heated moisture to your strands and scalp. With the hair dryer and plastic cap method, depending on how much moisture "lives" within the plastic cap (and the heat setting on the dryer), it too will provide the necessary heated moisture.
If you place conditioner on your hair and sit under the hair dryer without a plastic cap, this will not produce the same effect. The dry heat does not contain moisture and you basically would be drying the conditioner onto your hair. For some types of treatments this may be necessary, but if you're looking for added moisture and for your hair to receive the benefits of the conditioner, the previously mentioned method will not do.
If you're using the hair dryer and plastic cap method, you're receiving moist heat, cuticles being opened and the benefits from your conditioner. I believe the hair steamer is a wonderful treat and a preference; it is a bit different than the hair dryer and plastic cap method due to the direct and constant heated moisture. I personally like sitting under my steamer - plus with the steamer I have, I get to do a mini facial steam at the same time as I steam my hair. If you are not in the market to purchase a steamer, I do not think it is a necessity for you to do so (there are other options). However, if you ever have the chance to use one, do a comparison and determine if you feel it to be an investment or not.
Xs and Os