That's only a secondary reason, the main reason for this is to avoid having to deal with CSS' "everything is global" flaw.
CSS Modules [1] and other tools allow you to require CSS like you would with any other dependency, and replace named classes by unique hashes at build time. This prevents your CSS from leaking to elements that do not explicitly require it.
CSS Modules [1] and other tools allow you to require CSS like you would with any other dependency, and replace named classes by unique hashes at build time. This prevents your CSS from leaking to elements that do not explicitly require it.
[1] https://github.com/css-modules/css-modules