I have found that the "ship something then iterate" approach to software development can get stuck in local optima without a clear path to get out when it gets flooded by unforeseen problems. Then it becomes a maintenance nightmare. But by then the original developers will have moved on with their careers or they are just happy chugging along with the mess they've created because they're not competent enough to know better.
>good code is easy to change so it will easily get rewritten until it's not easy to change anymore
Sounds like the 'bad currency drives good currency out of circulation' problem. Bad code drives good code out, because good code is easy to understand and change.
Separating concerns, isolating things that are not related, these are some basic tenets of good engineering. Yet we all keep rolling the ball of mud downhill and act shocked it keeps growing and swallowing everything.
Legislatures write rules, people enter contracts, sue for perceived breaches and courts rule on these disputes. People then adjust behaviors to get desired results without incurring legal liabilities. Results vary across jurisdiction. Such questions can't be answered in principle. California famously won't enforce non-compete clauses, and that apparently helps innovation. China caught up industrially with the West within one generation by flouting every IP rule we have here. On the other side of the debate, patent trolls...
Attaining high level understanding and speaking convincingly about it are entirely different skills from knowing how to build it. Interviews are always a proxy anyway, your job will never be solely comprise of convincing people of your expertise. Sooner of later you have to do exercise it somehow. Unless you're the CEO, that is. The higher you go the easier it is to make a career out of being in the right places at the right times.