It is not capitalism but rather neoliberalism/monetarism that propels the trickle-down theory. The time period where grandfathers worked for the same employer and then got a pension coincided with the post-depression/WW2 period of Keyensianism when many western governments pursed full employment economies via fiscal policy.
In the period from the early 1970s onwards when neoliberalism/monetarism has been dominant, we have seen falling real wages, the financialisation of the economy (including the consumer credit explosion you describe), governments restricting themselves to managing the economy only through the very blunt tool of monetary policy (i.e. interest rates via a central bank).
I would argue that the symptoms we both identify are the result of neoliberal/monetarist policy rather than decreased demand for human labour. If governments still pursued full employment via fiscal policy things would be very different.