Language acquisition, a cognitive process, does not vary in response to any test, regardless of its design, just as an MRI doesn't alter brain function.
Cognitive scientists and academicians, unlike English language testing corporations, do not print brochures or pay teachers to convince students and parents to "read up about the CEFR" or IELTS or any other test 'product'. As I indicated above, in the academic community there is ongoing debate about the accuracy of ALL language testing, corporate and academic.

There is no debate about the fact that education does directly influence language acquisition. My 'reading up' is always an effort to improve my efforts in that venue. Every payment that I have received in China has come from non-profit academic institutions. I find them problematic enough. What I have observed in the testing and private education companies in China has been, quite frankly, appalling.