Why do we need a paid app to record audio from the system? Surely it's a small enough job for a small utility/script? This seems very Mac ecosystem to me.
Indeed. Windows has had a Sound Recorder since 3.1, and it's possible to record the currently playing audio if you select the right input (usually named "Stereo Mix" or similar.)
Support for the "Stereo Mix" audio source is a relatively recent thing - and my understanding is that, even now, it's driver-dependent. It most certainly wasn't available in Windows 3.1.