I can second the experience of the author. All in I had contact with over 40 different providers. I was lucky in that I had to leave my job and could concentrate on the administrative work required full time. I eventually learned I needed to keep a detailed written narrative up to date with a tl;dr at the top. Eventually I added appendixes that summarized lab tests and surgery reports. This was the only way I could make sure each provider had the details they needed. I would always send it advance, most of the time the doctor hadn't read it so I brought paper copies and sat there while they did.
The billing and who covered what was hopeless. I had to fight with medical insurance, the medical disability company and Medicare when I maxed both of those out. I went through every bill line by line to identify mistakes, there were many. Then I would make sure each had received a copy of each bill and start figuring out who would cover what, sometimes line-by-line. This all had to be done over phone and fax.
It's broken and I am sure it's killing people. I also don't see a technology fix. Anything that requires more than two or three providers is an edge case, this space is 90% edge cases.