CSS does have a preference. CSS has absolutely 0 knowledge of your BEM hierarchy, they're just different names as far as its concerned. The developer has just

CSS does have a preference. CSS has absolutely 0 knowledge of your BEM hierarchy, they're just different names as far as its concerned. The developer has just chosen to pretend that a hierarchy exists where there is none. CSS cannot do trees, but it can do logical AND and OR, so you can somewhat express a hierarchy as a union of the different levels of your tree, so .button.login.green has a logical meaning in CSS where .button__login--green is no different than using .pinapple as a class name.