you check in the uncompressed audio, and then fmod, wwise or whatever other middleware you're using will compress to a different format and compression ratios on a per-platform basis during the build process (i.e. vorbis on PC, AT9 on PS4, FADPCM on mobile, etc.)

Yeah that makes sense, but the person I replied to suggested that the end user's assets would be uncompressed as well.

The only scenario I can think of is games supporting surround sound which can't afford the extra cycles of decompression.

Titanfall was infamous for this[0]

  PC gamers (especially those with SSDs) were puzzled to find out that Titanfall had a gargantuan 48 GB file size, despite the lack of a single player campaign and the fact that it was running on a modified source engine. Some digging around in the files revealed that a huge portion of that size was due to a whopping 35 GB of completely uncompressed audio. Respawn has now explained that the reason the audio was not compressed was so they could dedicate more system resources to running the game, and less to unpacking audio files.
  ...
  He did, however, admit that most PC gamers probably wouldn’t even notice the difference. “On a higher PC it wouldn’t be an issue. On a medium or moderate PC, it wouldn’t be an issue, it’s that on a two-core [machine] with where our min spec is, we couldn’t dedicate those resources to audio.”

[0] https://www.escapistmagazine.com/titanfall-dev-explains-the-...

I was looking for a good reason why this might be and all I could find was an old HN thread suggesting that uncompressing audio takes CPU cycles so leaving it uncompressed helps to avoid CPU bottlenecks when you have a game that might be playing a lot of sfx at once

There was a heavily publicized instance of this a decade or so ago with (I think) Titanfall, but I don't think it's the norm at all.