So many people think forks are bad for programming because they split the developers. It does this, but it is still an overall positive.
Forks help programs become the best versions of themselves. With Sudo, you have programs like DoAS that are becoming popular on desktop Linux, and this makes sense because, for desktop users, it is a better experience, so it is popular.
Development can be slower because there will be fewer people making one product, but this will make it better for the consumer because over time the product will get better and you can pick what version of a program is the best. With youtube-dl, the product may work and was the first, but YT-DLP is better and is a fork. Because YT-DLP is an overall better product, people will pick it.
Rewrites are also good because they will help against local minima, which happens if you have a product and base it off of some code that works but is not the best. But because the program is inherently bad, no matter how many changes you make, it can't be the best. Rewrites can make a project the best it can be. Like Wayland is kinda like a rewrite of X11, where it is just the better version and improves on what X11 could not change.