It means that Windows/Microsoft doesn't provide anything to driver writers or DAW authors.
MS tried a bunch of tech in the past (WinMM, MCIWnd, DirectSound, WaveOut, WASAPI, XAudio2, etc), but none of them ever worked for professional Audio.
The proper solution was always to use ASIO, which is third-party technology by Steinberg. It works but it's not integrated with Windows: it goes directly to the audio interface, bypassing stuff in the Kernel.
This bypass causes some limitations, such as not being able to use the system mixer (which prevents from using media players or multiple audio apps), or sometimes having different audio-interfaces not work well with each other.
There are workarounds to those issues, but they have to be handled by the interface manufacturer when writing the drivers. Also, you can't have low-latency with built-in soundcard unless you use something like ASIO4ALL, which is not super stable IME. This sucks when you want to work on-the-go with headphones.
Of course, it can be very stable when you use the right combination of DAW, drivers and sound interfaces, but when you don't you have problems.
On macOS and iOS? CoreAudio is native and it has super low latency by default. It's mostly plug and play and all apps use it. It even provides APIs to use Audio Plugins or reroute Audio, so DAW writers don't even have to write it themselves (unless they want to). Do you have multiple Audio/MIDI interface? In macOS there's a built-in app to "link" them together.
MS tried a bunch of tech in the past (WinMM, MCIWnd, DirectSound, WaveOut, WASAPI, XAudio2, etc), but none of them ever worked for professional Audio.
The proper solution was always to use ASIO, which is third-party technology by Steinberg. It works but it's not integrated with Windows: it goes directly to the audio interface, bypassing stuff in the Kernel.
This bypass causes some limitations, such as not being able to use the system mixer (which prevents from using media players or multiple audio apps), or sometimes having different audio-interfaces not work well with each other.
There are workarounds to those issues, but they have to be handled by the interface manufacturer when writing the drivers. Also, you can't have low-latency with built-in soundcard unless you use something like ASIO4ALL, which is not super stable IME. This sucks when you want to work on-the-go with headphones.
Of course, it can be very stable when you use the right combination of DAW, drivers and sound interfaces, but when you don't you have problems.
On macOS and iOS? CoreAudio is native and it has super low latency by default. It's mostly plug and play and all apps use it. It even provides APIs to use Audio Plugins or reroute Audio, so DAW writers don't even have to write it themselves (unless they want to). Do you have multiple Audio/MIDI interface? In macOS there's a built-in app to "link" them together.