In the UK you can still find proper butchers where they cut meat directly from the carcass. If you ask they will often give you the bones. There are some that will charge but I avoid those.
I use a pressure cooker to save time.
I do agree that the long slow cooking was traditionally how it was done but that was when they had solid fuel cookers and the range was warm 24/7 and the stock pot was always on. I'm afraid in modern homes the condensation and smell permeating the house would be too much for most readers.
Stephan on soup stock don't forget the vinegar to increase calcium/mineral content.
I generally saw up as many bones as I can get in the pressure cooker and make as much concentrated stock as I can. I then put the concentrated stock in the freezer so it's there when needed to make soup.
I think one of the reasons we've gone wrong with food is that we've separated the meat from the bones.
In ancient cultures we know what they were eating from the bones and we also know how the bones were crushed/ broken to extract the goodness inside. Now all that goodness is wasted because we just want the meat. It's chicken breasts that are expensive and the chicken carcass that's wasted. Maybe we should be investing in the largest slow cooker we can find/accommodate and get back to basics.