Setups for professional music production. This usually requires JACK (https://jackaudio.org/) as audio server, which allows synchronizing and connecting multiple applications.

For example, you can have Ardour (https://ardour.org/) as DAW, but use another application like Hydrogen (http://hydrogen-music.org/) for creating drum samples. JACK connects the two applications using a virtual patchbay that allows using Hydrogen as an Input for Ardour. Essentially any application can be an input and/or an output.

JACK also provides synchronization using a "master clock", so that Hydrogen starts playing as soon as you hit the "record" button in Ardour.

Many people also use a Linux kernel optimized for low latency audio.

With PulseAudio, these things are not possible. On the other hand, consumer applications like web browsers don't usually offer direct JACK support. So bridging is necessary, by using PulseAudio as a JACK input.