Where you start matters. For example, when it comes to designing a new amplifying circuit, if your starting point is first the amplification path and second the power supply, you’ll get a very different amplifier than if you reversed the two.
If instead, your starting point focused first on building the perfect power supply and second adding the best means of modulating that supply (in cadence with the incoming audio signal), your design would likely be very different than the first example.
It’s all a matter of viewpoints and priorities.
An amplifier is a valve at the end of a power supply but also a valve fed from a power supply. The difference is one of perspective.
In my experience, designers who understand the critical role power supplies play in sound quality make far better sounding designs than those that just tack on a decent regulator and call it a day.
Where you start always defines where you end.