Thanks. This alone could be enough validation. I worked only in smaller codebases but I get sometimes it is impossible to untangle a tech debt -- much easier to just ask for a new copy of the requirements and start over, which also has the benefit of triggering things such as "Oh we actually don't need A,B and C, don't bother with them".

Main problem isn't sheer amount of code. Problem is that X11 have to somewhat stick to protocol so apps written in 1995 keep working on top of it.