Corporations are keen to avoid interference in their business through taxation and/or regulations. A CSR program can persuade governments and the public that a company takes health and safety, diversity and the environment seriously, reducing the likelihood that company practices will be closely monitored.
I think that this often is the main reason for advertising CSR. By awarding suppliers with “Gold” who do not allow their own employees to check the EcoVadis Premiom Report, EcoVadis helps their clients to avoid thorough audits. That is irresponsible.