This is interesting, because I've also seen something that is quite the opposite. A codebase where an initially a small but quite inexperienced team wrote most of the original code and while these people are in fact still around they've been promoted to management roles based on their seniority in the company. Usually they never really advanced that far as software developers and are neither really experienced technically nor good technical managers.
These people protect and maintain the original code, architectures and practices almost reflexively. They resist better practices and refactoring, as well as education as they fear it will expose what they don't know. These companies also become a revolving door for anyone with any experience or talent for obvious reasons.
Honestly, I think the one of the worst problems for both codebase and technical culture is not beginning with a team of sufficient expertise and experience that can grow and mature appropriately over time.
The problem with technical management is often that good developers stay where they are (they are NEEDED), but bad developers are often promoted because it's convenient, and because they don't exactly cling to their technical position - they're expendable.
So you have people that were bad coders to begin with and that don't have lots of technical know-how and experience making decisions that impact the project in very bad ways (like choosing absolutely the wrong frameworks or tools that HAVE to be used).
Also, good engineering skill isn't rewarded, because - of course! - a management or team lead position has more status and salary than a technical position, because it's worth so much more to the company.
So you just presume I'm exaggerating? On the basis of what exactly?
There is nothing robust about mountains of spaghetti code. If anything these businesses are spending countless dollars paying the interest on the technical debt left here. What's worse is it impacts their long term competitiveness as it resists even incremental improvements. Besides, there is nothing fancy about basic practices like solid design, proper planning or even just the appropriate use of tools for source control and build processes.
These people protect and maintain the original code, architectures and practices almost reflexively. They resist better practices and refactoring, as well as education as they fear it will expose what they don't know. These companies also become a revolving door for anyone with any experience or talent for obvious reasons.
Honestly, I think the one of the worst problems for both codebase and technical culture is not beginning with a team of sufficient expertise and experience that can grow and mature appropriately over time.