We asked camera companies why their RAW formats are all different and confusing

Don't know what's confusing about it... I mean, I shoot ARW with my Sony, these work fine with Lightroom and work fine with DxO PhotoLab [1] at least as long as my ARWs are not compressed (it's not that the compression is proprietary, it's that the compression is lossy and breaks denoising)

[1] Shoot ISO 12,800, process with DxO, people will think you shot at ISO 200; makes shooting sports indoor look easy, see https://bsky.app/profile/up-8.bsky.social/post/3lkc45d3xcs2x so I got zero nostalgia for film.

Proprietary formats require 3rd party developers to adapt their tools: While most mainstream software will be updated to support most/all cameras, this makes it harder for smaller projects to do. If they used an open standard, the advanced features could still require additional work to be compatible (ex: If they store custom metadata), but you could normalize everything that's shared, ensuring the core capabilities will never break for a new camera with its updated proprietary RAW like it currently does.