It’s a much larger problem than that, I’ve already suggested something but we still have a lot of discussion to do before we change the logic.
The core issue is S3/whatever has no method to authenticate Strapi users so we have to proxy the files through the Koa server (and using the SDKs for each to fetch and not just upload/delete, leading to more complex upload providers).
The largest problem is that we are still using buffers and not streams which is why we have problems like: Multiple Image Uploads result in memory leak · Issue #6432 · strapi/strapi · GitHub
The upload plugin is due for a major refactoring in the future and this is one of the topics that I plan to raise with our Product and Engineering teams. (same for folders in the media lib)