Hi HoosierLife,
In general terms yes that’s correct. Outside of any stretch in the bladder itself … air doesn’t provide any progressive support and it’s either fully compressed or not compressed at all. Some airbeds have a separate section in the middle under the heavier part of the body that can be independently adjusted that would be an improvement but in general terms air isn’t an ideal support system.
There is also more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel”.
Phoenix