Home ageing affects someone’s ability to maintain a standalone forum? Do you mean lack of free time?
I'm not complaining most of the time, but sometimes I want to be able to spend a day working mindlessly on my computer to try new things and fool around.
One other factor not commonly mentioned is that many people ossify and have difficulty expending the mental energy to seek out new music. I personally don't do that anymore but I certainly did for a while when I was much more stressed out with work. Additionally, some genres themselves seem to get into a rut and tap out (let's not forget the "punk's not dead" attempts at denying reality, for instancee)