> But long before the rewrite project achieve feature parity with the original, it is already marred by the same issues that motivated the rewrite.
I think there are definitely counter-examples. Can you imagine using an OS in 2020 based on incremental improvements in Mac OS System 9, or Windows ME. Or browsing using a browser based on incremental improvements in Netscape 4.7?
Windows NT wasn't a rewrite of Windows 3.1, but an attempt of Microsoft to create a modern workstation OS that is in a completely different product category than DOS/Windows 3.1.