> In Linguistics the notion that a language is more difficult/complex than another is not accepted.

This is not quite true; it is widely accepted that certain languages are less complex than most others. A few languages can't be less complex without most languages being more complex.

Interestingly, among the examples of languages losing complexity due to real-world interactions are English and Mandarin Chinese, both of which endless people will be happy to tell you are uniquely difficult.