All of those are problems in practice. For some, there are mitigating effects, eg. many companies use code reviews or pair programming to ensure that there are multiple eyes on each section of code, or they rotate out tasks between programmers so that multiple people need to get familiar. For some (eg. the large codebase that got big but has no documentation, and all the original authors have cashed out their options and are sitting on a beach somewhere), it just sucks.

The thing is - being eclipsed by a faster, nimbler competitor who steals your market is a bigger problem. Bad code will make your programmers groan and occasionally threaten to quit, but it usually won't threaten the existence of an organization. A bad product will threaten the existence of an organization. So among surviving companies, code generally tends toward shitty, because the ones that spent a lot of time on code hygiene often went under during the growth & competition phase of the industry.