I for one believe that current approach of no code ownership is one of the main contributors to terrible quality and performance of modern software. People are

I for one believe that current approach of no code ownership is one of the main contributors to terrible quality and performance of modern software. People are just routinely modifying code they know very little about, it's pure insanity in my opinion. Let's hire 10 writers to work on the same novel where they're all allowed to make changes to any part of it, and see how good the result it... The main reasons companies prefer this way of working is the bus factor. Not even being hit by the bus per se, but just having only one expert on a given piece of the system gives him leverage in negotiating pay and working conditions - and most managers hate workers who are not powerless cogs (it' much easier to manage cogs than people), and they will sacrifice efficiency and product quality to reduce people to such status. There are a companies in niches where software quality and performance cannot be skimped on and they sometimes don't do "shared" code ownership (the alternative is to still do "shared" ownership and compensate via ungodly amount of testing to catch any issues before release - as far as I understand this is the approach in large companies that do critical embedded software - auto, medical etc.). Essentially I believe that code ownership is mostly practiced in small boutique companies which produce performance-sensitive software - somebody like an audio plugin maker etc. Everybody else, incl. web startups, went the way of the moloch via shared code ownership so that owners' and managers' jobs are easier.