I recently accepted a position at Amazon (have not started working there yet) and I have a similar experience.
The first part of the interview was exactly like the linked experience. No coding questions just reasoning. The second part I had to use ProctorU instead of Proctorio. Personally I thought the experience was super weird but understandable, I'll get to that later, somebody watched me through my webcam the entire time with my microphone on. They needed to check my ID before the test. They needed me to show them the entire room I was in (which was my bedroom). My desktop computer was on behind my laptop so I turned off my computer (I don't remember if I offered to or if they asked me to) but they also asked me to cover my monitors up with something which I thought was silly after I turned them off so I covered them with a towel. They then used LogMeIn to remote into my machine so they could check running programs. I quit all my personal chat programs and pretty much only had the Chrome window running.
The proctored section involved a work simulation and coding questions. Before the coding section started they opened up the Java 7 and 8 docs, C++ docs, and an online calculator in my browser so I could use those for reference. I could take a break in between the two parts but I didn't need to. In total it took about 3 hours for me to finish everything but they said to block out 4 hours. After that I got an offer.
I didn't talk a real person who actually worked at Amazon (by email or through webcam) until I received an offer.
I can understand why people would be bothered or disturbed by these practices but I just thought that Amazon has a ton of applicants and it would take more time for engineers to talk to applicants. In total it took about a month from when I first applied to when I got an offer. I was then flown out to visit Amazon (not for more interviews because I already had an offer) and I actually got a chance to talk to people and learn about teams and ask questions. Yes, I asked multiple different people about Amazon's problems and they all said that their personal experience has been fine but a few said that they know of people who have had bad experiences. Seems like it's dependent on your manager. I know somebody who works there now (not in engineering but works in Seattle) and they love it. I found a team I liked, I talked to people who worked on the team and they all greatly enjoyed it so I accepted after my visit. Everyone who I talked to seemed very passionate about what they do and all take ownership over their projects.
I also applied to other large companies at the same time as Amazon (Google, Microsoft, Facebook, Twitter). Microsoft and Facebook haven't sent me anything. There was a mixup with Google's emails so that delayed my interview process but by the time I started talking to them I had already pretty much made my mind up about Amazon. I didn't go through any real interview rounds with Google, just preliminary screening questions. Twitter sent me a coding challenge but their email also said that they wouldn't get back to people until mid December.