I'm not the best person to answer this either, but whenever anyone says old code is fragile and we should just throw it all out and start over, I always point at this, possibly famous post, by Joel Spolsky:
https://www.joelonsoftware.com/2000/04/06/things-you-should-...
Couple of key comments for me
"The idea that new code is better than old is patently absurd. Old code has been used. It has been tested. Lots of bugs have been found, and they’ve been fixed."
"It’s important to remember that when you start from scratch there is absolutely no reason to believe that you are going to do a better job than you did the first time. First of all, you probably don’t even have the same programming team that worked on version one, so you don’t actually have “more experience”. You’re just going to make most of the old mistakes again, and introduce some new problems that weren’t in the original version."
A similar analogy might be Chesterton's Fence, it's important to know why it's in the state it's in before you decide to alter it?:
https://fs.blog/2020/03/chestertons-fence/
Couple of key comments for me "The idea that new code is better than old is patently absurd. Old code has been used. It has been tested. Lots of bugs have been found, and they’ve been fixed."
"It’s important to remember that when you start from scratch there is absolutely no reason to believe that you are going to do a better job than you did the first time. First of all, you probably don’t even have the same programming team that worked on version one, so you don’t actually have “more experience”. You’re just going to make most of the old mistakes again, and introduce some new problems that weren’t in the original version."
A similar analogy might be Chesterton's Fence, it's important to know why it's in the state it's in before you decide to alter it?: https://fs.blog/2020/03/chestertons-fence/