I believe things that physically move (voice-coils, speaker cones, disc drives) will run in - like a car engine or motorcycle suspension.
I believe things have an optimum operating temperature window. This is achieved some time after switch on.
I believe components age and go out of specification. Occasionally out-of-spec components may change to being in-spec - but that is luck not design.
I believe that voltage drops at changes betwen metal types can create oxidation and change the electrical behaviour of a connection. Sometimes that is audible.
I believe that one gets psycho-acoustically more accustomed to the sound of a system over time.
I would never express my beliefs in the way that web-site does.