it’s not about “one more material design implementation”, “same components”, etc.
Nikita Sukhov

You are right about alternative for people. Also, can you told which library is deprecated? 
Yes, if I use react-toolbox, then I have to include support for CSS-Modules in my Webpack, but it doesn’t mean that I have to write my code only with CSS-Modules. With tools like Css-modules and JSS we don’t import unused CSS styles.
Also, why you decided to use this library, if you can use any approach that you want?