There's also a lot of great improvements in tooling that just completely outclass what CRA does. Webpack is a dinosaur that is slow and painful to use compared to new stuff like vite that is blazing fast and isn't written in JavaScript. Nextjs comes with a lot of routing decisions already made so it becomes much easier to quickly build apps on top of it
I am always amazed at how slow any build process that involves webpack always becomes.
Webpack runtime is well over 50% of the total time on our CI server builds, and that includes an installshield installer build and thousands of dotnet unit tests that are more complex than they ought to be in that pipeline.
That stuff is only blazing fast because it only targets greenfield projects and has no upgrade path for older projects with complex configurations (scratch "complex", any configurations).
