This is the big one for me. Just looking at the Create-React-App dependencies I can count 17 dependencies dedicated to interconnecting Webpack/Babel/ESLint/Jest/Terser/Typescript.

Plus there's the cost of having plugin-infrastructure and/or maintaining a public API inside the six tools themselves. Plus all of them have dependency on a parser.

Having it all in one single tool will tremendously reduce the amount of code necessary.