I don't really know if that is in the interest of the user. Just copying a file universally works with any file format and is a concept that users can understand.
A file has a name and a path, analogous to conventional storage systems. Putting it in a proprietary system like SharePoint or a Teams channel, to stay in the MS world, has other disadvantages.
I am giving them the benefit of the doubt, but sometimes I think the main goal for these "improvements" is vendor lock in, especially if the topic is around blurring file locations or URLs.
Access rights and relevancy of files is indeed something most alternatives organize better, but content tagging doesn't really work in my experience, because users just don't do it. So the only information about a files content remains the filename and the path.
Since those are fundamental concepts for data organization in most computer systems, it is advantageous to convey these ideas to the user and from my experience this is not that much of a hurdle.
Sure, a network share has disadvantages and without a competent clean up crew it quickly gets convoluted. But that is a problem all other systems have as well. So to improve the current situation, solutions should build upon file systems.
And asking the user if he really wants to save the file is probably just a good idea. If he ignores the message and throws away some work, he has learned a valuable lesson. Users on every knowledge level go through that experience at some point anyway. I think users suffer far more from most proprietary solutions for data exchange that is distinct from copying some files from A to B.