That's the way it's been for a long long time because it takes a long time[a lifetime for most] to pay off the mortgage.
Those baby boomers were also once youngsters who couldn't afford to get into property and then struggling to pay a mortgage once they had children. Perhaps even tougher when not so many women were working? They certainly had far less in material possessions.
That debt free property usually gets handed on to the next generation who can then clear their own debt.
If you are young and resent the current arrangement just bear in mind, that as you too grow old, any changes will effect you and your family too.
