The first three examples they use are filters.

The abstraction of impedance matching should be to "tune things to make them more efficient in their usability".

Their examples don't sit with impedance matching to me. They're all conversions or filters. The first thing was either not usable or they purely chopped off a part, not pointed it in the right direction.

In fact, the examples more or less all sit in a group in which impedance matching does not belong

Edit: the car transmission I'll give since there's a power vs speed decision that needs to be coupled