This problem is because the old guard wants to move on from the problems they created. They want to play with new toys. So they hire new devs to do the work they don't want and "free" themselves for greenfield development (i.e. the exact opposite of how it should be managed).
This would just massively increase churn. Old guys get sick of doing the same old crap especially when seeing the new guys get all the good stuff. So it increases the likelihood that people will just move around a lot more often in order to build that "new stuff". Eventually you'll have lots of companies saturated with "new stuff" that's no longer so new and nobody to maintain it because everybody knows the second you're too old in the company you get saddled with maintenance tasks.
> the old guard wants to move on from the problems they created
Just because it's old doesn't mean it's a problem. It still has to be maintained though, with higher effort since the technology may be outdated. Even the best designed systems become a chore to maintain when you have to do it for 10 years instead of doing anything new.
They had sent a new guy with essentially no training and he had not done a bad job. He was just new and needed time to get up to speed. When I started working with him he clearly knew what he was doing. But we got everything working 1 day after I showed up, because I had been deploying this product for a few years already.
Management basically praised me and shat on the new guy. I felt like crap and took new guy aside. We became friends, but this hurt his review later on.