Earlier quoted context omitted.
7z does not offer archive recovery. This has saved my archived data couple of times, which would be gone, if I was using 7z.
You can use an par2 file for that though. Yes, might be less convenient than having it built into the archive in some cases but on the other hand you can a) only download the .par2 file if you need it and b) use it to add error correction to files without putting them in an archive so you can access them directly and c) you can create the error correction information across multiple archives if you want.
I don't think you'll get why having all in a simple to use solution is superior for several of us.