This was already the case in the Firefox/Gecko project when I was participating 8 to 12 years ago (the repository goes back to late nineties). Understanding som

This was already the case in the Firefox/Gecko project when I was participating 8 to 12 years ago (the repository goes back to late nineties). Understanding some problems or coming up with a plan for how to fix an issue or build a new feature required extensive digging into the history of the code, with heavy usage of VCS history and "blame", issue tracker and code review comments, and often requiring pinging someone who has been there longer than you and knows some additional unrecorded context. It's a useful skill to have when developing or using open source software, as documentation is often lacking so being able to dig in and find out for yourself quickly is valuable, but having to engage all of that encoded knowledge/constraint space every time you go to edit code is a gigantic mental burden and slows down development pace. In my time there I'd estimate my ratio of time reading code to time writing code to be at least 90:10, maybe 95:5.