It not the HD tag that is the limitation here . it is the lack of such features in consumer camcorders
Prosumer ones are a notch above consumer ones and all have manual Focus ( Im not sure what over iris means)
they tend to cost a couple of thousand pounds give or take some though
You may be confusing control over aperture with focus control. You can get a shallow background with Auto focus
However the "Focus pull" in which you can decide whether you want to blur background or foreground or any partcular subject in a scene needs
MF and control over aperture , but the ability to do this may be limited by the small sensor sizes these camcorders have
Consumer camcorders do have some means of manual focus but it may be a rocker switch or touch menu (

)
However the size of sensors mean that they are optimised for fine focus rather than shallow DOF . As such even if you ar able to adjust the aperture wide open you may not get the shallow DOF you seem to desire