When you download a torrent, you’re downloading it from someone else’s computer. That ‘someone else’ is usually an individual, not some file sharing site with redundant servers.
When you download a torrent, someone had to send it. It’s a small cost for individual torrents, but they had to pay for energy, internet connection, hard drives etc. If more people seed the torrent, you get a small bit of it from each seed, spreading the burden.
If no-one with the torrent has their computer on and seeding it, you cannot download the file, because there is no-one to download it from. If there are several seeds with the torrent, then you can still download it even if one or more seeds turn the computer off at night, delete the file, or are overloaded.
Boeing doesn’t make many of the parts in the aircraft, especially things like pressurization controllers. Those come from contractors like Honeywell.
What they do is design the systems around the parts, including selecting the desired level of redundancy, and commission the custom parts needed.
The 737 is still mostly a 1960s design built mostly to 1960s rules. There have been plenty of improvements but that’s not the same as a clean sheet design built to be entirely automatic even when stuff breaks.