[zelphirkalt]

There are other arguments for rewrites usually though.

Some of the problems came only to light, because the original software was written and showed weaknesses. Of course afterwards one always knows more.

Then there is the reason of software often not perfectly matching your use-case and you could have better, specialized for your use-case software. You might also have other ideas about how extensible and modifiable your software should be. There really is a lot of software out there, that barely works for its use-case. If you are asked to extend that, good luck with that, without introducing new bugs, due to inflexible design.

So there are very valid reason for rewriting and often you do know better, how to write the software for your own use-case.