It's quite simple: Most people who work in software now aren't actually very good at their jobs, at least in terms of how that job would have been defined 15 years ago.
This is because incentives have changed such that being good at your job in your average mega-corp has very little to do with the outcome: To climb their ladder, you optimise for impact and move before you have to deal with the consequences.
When company is small and the leader is competent, it's easy to weed out incompetent employees. But beyond certain size, or when the leader themselves is incompetent, this becomes impossible, and the whole company starts to rot.
This is because incentives have changed such that being good at your job in your average mega-corp has very little to do with the outcome: To climb their ladder, you optimise for impact and move before you have to deal with the consequences.