My impression of FOSS is that it's very heavy on total rewrites, as that is what attracts engineers. So, you end up with a lot of underbaked variants of the same thing.
So I guess yeah if there are 100 ways to skin a cat you will get 100 different approaches, but then that's where the market comes along and mostly only the best 'rise to the top'.
Also, don't pretend complete re-writes with dubious value don't happen in big biz...its more common for something to be pronounced 'unworkable' and a complete rewrite mandate be issued, usually because a product had ossified to the point nobody knows what it actually does anymore, normally because companies are bad about investing maintenance time into code.