[pdkl95]

> come with pulseaudio by default

Which means they almost certainly include libasound.so, because PA still depends on ALSA in the kernel. Even in the case of distros that only use the ALSA emulation interface for PA, the traditional ALSA interface is still provided. Lots of software would break without that support.

It's more accurate to say most distros support both PA and ALSA by default.

> use pulseaudio successfully

Note that "successfully" doesn't imply "enjoyably" or "preferentially". I still hear complaints regularly from people that hate newer (PA-focused) distros that introduced a lot of latency problems. Movie audio sync became inconsistent (hundreds of ms latency, very high variability), and UI audio cues playing up to 3s (3000ms) after the visual changes.